It's definitely a more complete and well thought out solution than anything Microsoft has or ever has offered, not even to mention that it works more along the lines that I think about data access.
Aloha, Kevin One easy answer is to dump the pathetic MS offering and use something better with a decent interface like llblgen pro.
I then opened another project with another Linq to SQL model and it too fails with the same error. At this point I turned to Google to search and sure enough this has been found on a few occasions (like this post from Michael James).
As Michael points out the fix is to reset the Visual Studio Packages.
I was able to get into VS in Safemode and reset the toolbox that way.
Imagine having to deal with this sort of issue without the resources of shared knowledge.
Search for updating dbml:
Undoing checkout on the dbml file from TFS then rebuilding while the project is still checked out will allow the build to succeed, but as soon as undo on the project or check in on the project is done the build fails again.