I have spent the morning struggling with Visual Studio. It has been crashing non-stop, but I have got to the bottom of the problem, and am happy to share with the rest of the world.
Visual Studio was happily starting and loading my solution, but whenever I clicked on the test menu and attempted to do something like open the TestView window, VS was crashing. If I tried to open a localtestrun.testrunconfig file it would crash with the following error "Could not open assembly System.Data version 126.96.36.199 .... The system cannot find specified path".
I won't bore you with the process I had to go through to find the resolution, but the problem turned out to be that this morning My machine installed some updates from Windows Automatic Updates. Most of these updates were succesful, but one of them, namely "Security Update for Microsoft .NET Framework, Version 2.0 (KB922770)" had failed with the following error "Error Code: 0x643". after doing a search on this particular error I found the following article http://support.microsoft.com/kb/923100. However, I did not need to follow the resolution outlined there, I simply went to the Windows Update site and manually installed the update.
I hope this helps someone out before they have to spend half a day like I did trying to track it down.