Can't create Linq to Sql Classes

All of a sudden Visual Studio 2008 is producing errors whenever I try to open a Linq to Sql class, or create a new one:

Error 1 Could not retrieve the current project.  1 1 C:\webs\dmali\
Error 2 The custom tool 'MSLinqToSQLGenerator' failed.  Could not retrieve the current project. C:\webs\dmali\App_Code\DataClasses.dbml C:\webs\dmali\

I tried reinstalling VS but had no luck. Prior to this problem, I've been using the Linq to Sql designer for a few weeks without a problem.  I've never had any Beta bits on this machine, but I did have VS2005 on it before I upgraded to 2008.

Thanks,

John