I am currently using TFS with Visual Studio 2010 Ultimate and getting this error when I try to open up my solution:
The associated source control plug-in is no
It sounds like your bindings to the TFS server are messed up in your solution file. You should try removing the bindings manually in there by editing the solution file using a text editor.
There should be a Global section in the file, which is where all of the settings for this are located. look for GlobalSection(TeamFoundationVersionControl) and remove that entire section down to EndGlobalSection.
Once you do that, reload the solution and tell it to go back online and your bindings should be working again.