Request for the permisson of type 'System.Web.AspNetHostingPermission.. ' failed

I hope this is the appropriate group for posting this question.

We have a Web Application Project that compiles using Visual Studio
2005 on Windows XP but it won't compile on Windows Vista.

The error is:
'Request for the permission of type
'System.Web.AspNetHostingPermission, System, Version=2.0.0.0,
Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.'

I checked the Output window and noticed it happens in the step where
it runs LC.exe.

Any help would be greatly appreciated.

Thanks,
Clint