is not a valid Win32 application. (Exception from HRESULT: 0x800700C1)

While tranferring my development environment onto my newly installed Windows Vista x64, I came across the above somewhat cryptical error. Exception Details didn't exactly prove useful either: Exception Details: System.BadImageFormatException: is not a valid Win32 application. (Exception from HRESULT: 0x800700C1) A little Yahooing quickly provided some insight. Sitecore 5.3 doesn't cope all to well when being executed as an x64 IIS Application. The essence of the article, came down to just this: cscript %SystemDrive%\inetpub\AdminScripts\adsutil.vbs set w3svc/AppPools/Enable32bitAppOnWin64 1 However, the article is fairly old. And the admin scripts he is referring would not normally be part of your Vista IIS 7 installation. You need to install the IIS 6 Compatibility scripts for it.

Executing the command line and a quick IISRESET just for good measure, and all the problems went away. Now I doubt running Sitecore 5.3 in this way is really supported, but it gets the job done. I will keep a lookout for side effects.