TFS Team Build - Build fails if app_code references another project in the solution

I've using Team Build 2010 for some time开发者_运维技巧, and it suddenly stopped working after some changes in the code.

More specifically, when some file in App_Code used a reference from another project in the solution. I get this error message:

c:\Builds\Venus\Sources\Branches\xxx\xxx\xxx\App_Code\xxx.cs (9): The type or namespace name 'xxx' does not exist in the namespace 'xxx.xxx' (are you missing an assembly reference?)

Is it a known problem? Is there a workaround ?

I already tried deleting and redownloading the whole workspace but got no luck.

Thanks in Advance

This happened to me after doing a move to a web application project from a web site project. If your project is a web application project, then move the files out of the App_Code folder and delete it.