UBB.Developers Forums UBB.threads 7 Development How Do I? Problems upgrading to new beta5

I'm using Windows 2000/IIS to run the software. I installed the new version on my test server, and it worked fine. I installed it on my main server and I"m getting:

Error in CGI Application -

The specified CGI application misbehaved by not returning a complete set of HTTP headers. The headers it did return are:

and the rest is a blank white screen.

Does anyone have any ideas as to what could cause this? Thanks