Windows 8.1 can't start Powershell from a cmd or powershell prompt - "This app can't run on your PC"
<p>Powershell suddenly quit opening from both cmd and powershell prompts.  I haven't installed anything new between when it did work and when it quit working.</p>

<p>When I try to start powershell.exe from a cmd window (both elevated and not elevated) with the following command</p>

<pre><code>C:\Users\myuser&gt;powershell.exe
</code></pre>

<p>I get a popup error from the OS that says:</p>

<pre><code>This app can't run on your PC
</code></pre>

<p>Once I close that popup the cmd prompt I made the call from then prints:</p>

<pre><code>Access is denied
</code></pre>

<p>To the screen (yes even when I do this in an elevated cmd prompt)</p>

<p>When I try to do it in powershell with the following command:</p>

<pre><code>PS C:\Users\myuser&gt; powershell.exe
</code></pre>

<p>I get:</p>

<pre><code>Program 'powershell.exe' failed to run: The specified executable is not a valid application for this OS platform.
At line:1 char:1
+ powershell.exe
+ ~~~~~~~~~~~~~~.
At line:1 char:1
+ powershell.exe
+ ~~~~~~~~~~~~~~.
    + CategoryInfo          : ResourceUnavailable: (:) [], ApplicationFailedException
    + FullyQualifiedErrorID : NativeCommandFailed
</code></pre>

<p>Apparently even powershell doesn't like powershell anymore.</p>

<p>I've tried restarting the computer and that didn't fix it, but I'm totally stymied as to what to do next.</p>