Configuration:
I personally encountered some comparable problem: Visual Studio 2010 did not begin debugging but froze.
When I clicked VS it displayed a "Wait some more" or "Switch to" message box which didn't help me.
Using a task manager I could kill the *.vshost.exe process which brought VS back to life but aborted the debugging. Launching the program without debugging started the application instantly.
Solution:
Disable the indexing service for your code directories! Either deactivate the index service or uncheck the folders in the Indexing Service control panel.
I just closed and reopened VS. This seemed to fix my problem
I've got a similar setup and I'd followed all the suggestions here and on Microsoft Connect - none of which worked for me. The only thing that did work was renaming MSVSMON.EXE in the x64 folder to MSVSMON.EXE.OLD and copying in the file from the x86 folder in it's place. I'm not sure if there are any other implications in doing this but it seems to have solved the problem in my case.
Seen a similar issue when running both Visual Studio 2010 and Visual Studio 2012 at the same time. Closing Visual Studio 2010 allow the debugger to start working in Visual Studio 2012.