I opened my vs2010 solution with vs2012 but it didn\'t make any conversion as from 2008 to 2010 was happening. So my solution still remains the same as 10 label on it. when
This is slightly different, but along the same lines so in case it helps anyone:
I was loading a project where it looked like it was loading and then kept showing all projects as unavailable. No errors were on the migration report. I tried reloading the solution and projects many times, using various methods including suggestions here.
Finally I found a "Resolve Errors" option when right clicking on the solution in the Solution Explorer. VS went through a load process again and it worked; no problems.
I don't know what it did differently that time, but apparently it made a difference.