When assembly is inside 'C:\Windows\System32' i get 'Unable to find a version of the runtime to run this application'

Question

I'm currently writing a screensaver using C# and the express version of VS2010. I've created a nice little screensaver and renamed the resulting assembly to have a *.scr extension.

When i place this on my desktop and double click it (or select configure from the context menu), it runs fine and displays the correct form/screensaver. However, when i install this by placing it into the C:\Windows\System32 folder, i try double clicking on it and get this error:

Unable to find a version of the runtime to run this application

Also it doesn't work from the screensaver control panel. It's listed in the drop-down but it doesn't function.

Any idea what is going on?

Don't copy assemblies into this private Windows directory. It is redirected on a 64-bit operating system. — Hans Passant, May 03 '11 at 00:36
That's probably it! What do you mean by redirected though? And how would i install a screensaver if not into the 'system32' dir? — Gary Willoughby, May 03 '11 at 16:30

score 6 · Accepted Answer · answered May 03 '11 at 17:54

The problem is that the screensaver was compiled for 32bit cpu. Only 64bit exes are allowed in the %WINDIR%\System32 folder on a 64bit OS. Which in fact, i was using Windows7 64bit.

The correct place to put 32bit screensavers is in %WINDIR%\SysWOW64 or compile using 'AnyCPU' option in Visual Studio then you can install into the %WINDIR%\System32 for all.

When assembly is inside 'C:\Windows\System32' i get 'Unable to find a version of the runtime to run this application'

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