"Projects have recently been added to this solution. Do you want to get them from source control?"
So, we have been getting this message every time we open our .sln file from VSTFS Source Control...Turns out there is a fix.
The quick steps:
Unbind the solution from TFS (Do this by going to File/Source Control/Change Source Control menu item)
Edit the .sln file manually and remove all sections that look like "GlobalSection(TeamFoundationVersionControl) = preSolution". Yes these sections look important, but they aren't really at this point. And also, by section I mean from that GlobalSection line all the way down to the next "EndGlobalSection" tag and all the contents in between, not just the tag itself.
Rebind the solution with TFS (Same place as step #1)