While playing with IIS 7 I accidental destroyed my IIS (XML) settings file. To fix this problem I copied the .XML from a colleague PC to mine. After this my IIS started giving a strange error:
HTTP Error 404.17 – Not Found – The requested content appears to be script and will not be served by the static file handler.
After a quick search I found out that I copied the .XML from a 32 bit PC to my 64 bit Vista and that all my Application Pools where now running on 64-bit. So my application stopped working because it's 32 bit.
To fix this problem go to IIS, right click your Application Pool and set the Enable 32-bit Applications to true.