Just and update on some frustrating behaviour I recently had.
The solution is so simple it's annoying to let anyone else struggle with it...
Well, I went ahead and installed SharePoint 2010 on my Win7 64 bit laptop.
In stand alone mode, everything was going great!
here is a link to a great step by step guide for doing that: http://msdn.microsoft.com/en-us/library/ee554869.aspx
OK, once I was done - SharePoint was working great and at lightning fast speed!
Next I wanted to install Visual Studio 2010 on that same machine, so I ran the installer and chose to install C#, Web developer and among other things the SQL express that comes with it.
Installation, again, was going smoothly.
After a reboot - I noticed that SharePoint had stopped working, and any page I tried to access gave me server error 500... even the central administration!
Naturally, I ran the SharePoint configuration wizard and hoped it will make everything better again... only to find out it reports that my configuration database is not available!
So, first step was to fix the DB not available thing... that was easy:
apparently installing VS with its SQL express had stopped the SharePoint SQL instance and all I had to do was to start it, using services or using the start menu -> "SQL Server Configuration Manager":
OK - that allowed me to complete the SharePoint configuration wizard, but did not resolve the server error 500 I keep getting hitting any SharePoint page.
SharePoint log files were useless, which means that the error came before SharePoint code was even called.
Windows log viewer was very helpful on this, reporting an ISAPI filter that could not be loaded and caused the site load to abort: "Could not load all ISAPI filters for site/service. Therefore startup aborted"
Followed by another message:
"ISAPI Filter ‘C:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet_filter.dll’ could not be loaded due to a configuration problem. The current configuration only supports loading images built for a AMD64 processor architecture. The data field contains the error number. To learn more about this issue, including how to troubleshooting this kind of processor architecture mismatch error, see http://go.microsoft.com/fwlink/?LinkId=29349."
After a little trial and error, I have noticed that the ISAPI filter DLL file is being loaded from the 32 bit framework folder. Changing that manually to 64 bit in all my sites solved the problem!
So, while I am not sure of why this is happening, but at least here is how to fix it!