Most of the existing answers explain the *How*, but very few explain the *Why*. And before you go around executing code from strangers on the Internet, especially code that disables security measures, you should understand exactly what you're doing. So here's a little more detail on this problem.

From the TechNet [About Execution Policies Page][1]:

> Windows PowerShell execution policies let you determine the conditions under which Windows PowerShell loads configuration files and runs scripts.

The benefits of which, as enumerated by [PowerShell Basics - Execution Policy and Code Signing][2], are:

>* **Control of Execution** - Control the level of trust for executing scripts.
>* **Command Highjack** - Prevent injection of commands in my path.
>* **Identity** - Is the script created and signed by a developer I trust and/or a signed with a certificate from a Certificate Authority I trust.
>* **Integrity** - Scripts cannot be modified by malware or malicious user.

To check your current execution policy, you can run [`Get-ExecutionPolicy`][3]. But you're probably here because you want to change it.

To do so you'll run the [`Set-ExecutionPolicy`][4] cmdlet.

You'll have two major decisions to make when updating the execution policy.

### Execution Policy Type:

* **`Restricted`**† - No Script either local, remote or downloaded can be executed on the system.
* **`AllSigned`** - All script that are ran require to be digitally signed.
* **`RemoteSigned`** - All remote scripts (UNC) or downloaded need to be signed.
* **`Unrestricted`** - No signature for any type of script is required.

### Scope of new Change

* **`LocalMachine`**† - The execution policy affects all users of the computer.
* **`CurrentUser`** - The execution policy affects only the current user.
* **`Process`** - The execution policy affects only the current Windows PowerShell process.

† = Default

*For example*: if you wanted to change the policy to RemoteSigned for just the CurrentUser, you'd run the following command:

```lang-none
Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser
```

**Note**: In order to change the Execution policy, you must be running **PowerShell As Administrator**.
If you are in regular mode and try to change the execution policy, you'll get the following error:

>Access to the registry key 'HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\PowerShell\1\ShellIds\Microsoft.PowerShell' is denied. To change the execution policy for the default (LocalMachine) scope, start Windows PowerShell with the "Run as administrator" option.

If you want to tighten up the internal restrictions on your own scripts that have not been downloaded from the Internet (or at least don't contain the UNC metadata), you can force the policy to only run signed scripts. To sign your own scripts, you can follow the instructions on Scott Hanselman's article on [Signing PowerShell Scripts][5].

**Note**: Most people are likely to get this error whenever they open PowerShell because the first thing PowerShell tries to do when it launches is execute your user profile script that sets up your environment however you like it.

The file is typically located in:

```lang-none
%UserProfile%\My Documents\WindowsPowerShell\Microsoft.PowerShellISE_profile.ps1
```

You can find the exact location by running the PowerShell variable

```lang-none
$profile
```

If there's nothing that you care about in the profile, and don't want to fuss with your security settings, you can just delete it and PowerShell won't find anything that it cannot execute.

 [1]: http://technet.microsoft.com/library/hh847748.aspx
 [2]: http://www.darkoperator.com/blog/2013/3/5/powershell-basics-execution-policy-part-1.html
 [3]: http://technet.microsoft.com/library/hh849821.aspx
 [4]: http://technet.microsoft.com/library/hh849812.aspx
 [5]: http://www.hanselman.com/blog/SigningPowerShellScripts.aspx

I am trying to run a `cmd` file that calls a PowerShell script from `cmd.exe`, but I am getting this error:

> `Management_Install.ps1` cannot be loaded because the execution of scripts is disabled on this system.

I ran this command:

```lang-none
Set-ExecutionPolicy -ExecutionPolicy Unrestricted
```

When I run `Get-ExecutionPolicy` from PowerShell, it returns `Unrestricted`.

```lang-none
Get-ExecutionPolicy
```

Output:

```lang-none
Unrestricted
```

***

> cd "C:\Projects\Microsoft.Practices.ESB\Source\Samples\Management Portal\Install\Scripts\"
> powershell .\Management_Install.ps1 1
>
> WARNING: Running x86 PowerShell...
>
> File `C:\Projects\Microsoft.Practices.ESB\Source\Samples\Management Portal\Install\Scripts\Management_Install.ps1` cannot be loaded because the execution of scripts is disabled on this system. Please see "`get-help about_signing`" for more details.
>
> At line:1 char:25
>
> + `.\Management_Install.ps1` <<<< 1
>
> + CategoryInfo : NotSpecified: (:) [], PSSecurityException
>
> + FullyQualifiedErrorId : RuntimeException
>
> C:\Projects\Microsoft.Practices.ESB\Source\Samples\Management Portal\Install\Scripts\> PAUSE
>
> Press any key to continue . . .

***

The system is [Windows Server 2008][1] R2.

What am I doing wrong?

 [1]: https://en.wikipedia.org/wiki/Windows_Server_2008

PowerShell says "execution of scripts is disabled on this system."

In addition to the current answer, here's a guide with some alternative formatting and pictures (though the steps largely remain the same. Adapted from to [Enable Aero Desktop Experience in Windows Server 2008 R2][1]

### First, **Install Desktop Experience in Windows Server 2008 R2**:
1. Click Start > Control Panel > Programs & Features > Turn Windows Features on or off.
2. In the Features Summary section, click Add Features.
     * ![Add Features][2]
3. Select the Desktop Experience check box. 
     * ![Desktop Experience][3]  
   Install additional features if prompted
4. Click Install, you might have to restart your Windows computer.

### Next, **Enable the Themes service**:
1. Click Start > Control Panel > Administrative Tools > Services.
2. Click Themes.
     * ![Themes Service][4]
3. In the Startup type list, select Automatic and then click Apply.
     * ![Startup: Automatic][5]
4. Under Service status, click Start and then click OK.

### Finally, **Select an Aero theme**:
1. Right-click on the desktop & select Personalize.
2. Click Themes.
3. Under Aero Themes, click an Aero theme.
     *  ![Aero Theme][6]


  [1]: http://www.thewindowsclub.com/enable-aero-desktop-experience-in-windows-server-2008-r2
  [2]: https://i.stack.imgur.com/86Z1b.png
  [3]: https://i.stack.imgur.com/hMRer.png
  [4]: https://i.stack.imgur.com/nMSzm.png
  [5]: https://i.stack.imgur.com/rXlsA.png
  [6]: https://i.stack.imgur.com/5fRBZ.png

I'm using Windows Server 2008 R2 as a Workstation and would like to enable Aero Glass for some software development. Is there a way to enable Aero Glass on Server? 

Thanks in advance, 

NieAR

Enabling Aero effect in Windows Server 2008 R2

## Diagnosing

In terms of diagnosing what App Pool is causing trouble, you can:

1. Select the server
2. Go to IIS > Worker Processes

![Server Settings][1]

This should bring up a menu like this so you can determine which App Pool is running amok.

![Worker Processes][2]

From there you can simply restart the the app pool and 9 times out of 10 that will fix any immediate issues you're having.

## Treating

Unless you run some sort of controversial business, this is probably not a DDOS attack. It's likely that some code is just hanging because it couldn't get through to another server or got stuck in a loop or mis-allocated resources or your app pool just hasn't been recycled in a while.

You can deal with this problem programmatically without having to manually identify, log in, and recycle the app pool. Just configure the [CPU property][CPU] on your App Pool. You can have it kill (and automatically restart) your process anytime you reach a CPU threshold for a certain amount of time. 

In your case, if you want it to restart at 80%, you can right click on the app pool and go to Advanced Settings and apply the following configurations:

![App Pool Advanced Settings][3]

**NOTE**: As [kraken101](https://stackoverflow.com/users/1496138/) pointed out, different IIS GUIs have treated this differently over time. While the config value is always in 1/1000 of a %, sometimes the GUI takes the whole percent.

You can add this to [your config][iis config] section like this:



 <applicationPools>
 <add name="DefaultAppPool">
 <cpu limit="80000" action="KillW3wp" resetInterval="00:01:00" />
 </add>
 </applicationPools>

Alternatively, you could script it with Powershell's [WebAdministration Module][IIS-Admin] like this: 
(*[make sure web-scripting-tools is enabled][Web-Scripting-Tools])

 Import-Module WebAdministration
 
 $appPoolName = "DefaultAppPool"
 $appPool = Get-Item "IIS:\AppPools\$appPoolName"
 $appPool.cpu.limit = 80000
 $appPool.cpu.action = "KillW3wp"
 $appPool.cpu.resetInterval = "00:01:00"
 $appPool | Set-Item

## Preventing

The steps above will help fix some things once they've broken, but won't really solve any underlying issues you have.

Here are some resources on doing performance monitoring:

* [Troubleshooting High CPU in an IIS 7.x Application Pool][4]
* [MSDN - Performance Tuning and Monitoring][5]
* [IIS Extension - Web Performance Monitor][6]
* [Troubleshooting Failed Requests Using Tracing][7]
* [PerfMonitor][8]
* [Log Parser][9]



 [CPU]: http://www.iis.net/configreference/system.applicationhost/applicationpools/add/cpu
 [IIS-Admin]: https://technet.microsoft.com/en-us/library/Ee790599.aspx
 [Web-Scripting-Tools]: https://stackoverflow.com/a/24393229/1366033
 [iis config]: https://stackoverflow.com/a/8650721/1366033

 [1]: http://i.stack.imgur.com/idFQ4.png
 [2]: http://i.stack.imgur.com/AD0pX.png
 [3]: https://i.stack.imgur.com/h6psb.png

 [4]: http://www.iis.net/learn/troubleshoot/performance-issues/troubleshooting-high-cpu-in-an-iis-7x-application-pool
 [5]: https://msdn.microsoft.com/en-us/library/Bb727100.aspx
 [6]: http://www.iis.net/downloads/community/2007/01/web-performance-monitor
 [7]: http://www.iis.net/learn/troubleshoot/using-failed-request-tracing/troubleshooting-failed-requests-using-tracing-in-iis
 [8]: http://bcl.codeplex.com/releases
 [9]: http://www.microsoft.com/en-us/download/details.aspx?id=24659

My CPU usage is 100% most of the the time in Windows Server 2008-R2 with my own vps, vmware, quad core, and 4GB Ram. When I open windows Task Manager and go to the resource monitor I see that 100% usage is because of `workerprocess.exe`.  I have 3 websites in my IIS.  

* How can I figure out which web site causes that usage
* How can I limit it to 80% usage of CPU?  
* Could it be a DDOS attack?  
* Is there any way to prevent DDOS?  
 
I installed eset-nod32 on my vps, but it doesn't show any attack in the logs.  I've tried searching about IIS and preventing DDOS, and just found an extension for banning IP addresses, but how can I find which IP address are generating traffic?  


The web site is written in `ASP.NET` and `C#`. How can I determine what is happening on that web site and which lines of codes are causing that cpu usage?

Also, one of my web sites should access administrator's desktop and read and write some files.  So because of that I changed its application pool -> identity (Process Model) to local system, and I don't know if it is related with the CPU usage or not.
