Have you tried debugging your web application. You might consider changing your web.config to allow for more verbose and meaningful error messages.
In the section
<system.web> of web.config do this:
<customErrors mode="Off"/>
This will turn off friendly error messages and they'll be replaced by more meaningfull stuff. Of course you shouldn't do this in a production environment since your users would probably not be amused. After you made those changes you'll have to wait a bit until the application restarts itself (after it detected the change in web.config).
Please try again and modify your question by adding the complete error message that gets dumped on the browser screen. Thank you!
Cheers
Manfred
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