Monodevelop Freezes on Windows 7 64bit

I saw a few posts about either Unity or MonoDevelop hanging but no real answers (maybe there is not one). The issue is that most of the time while running Unity I switch back to MonoDevolop I get the little blue circle and the IDE window fades (busy). Running 3.1.0f4 this happens consistently on several Windows 7 - 64 bit machines in the office but consistently never happens on my (or any one else's) MacBooks with the same project. I also noticed this briefly while running 3.0 on WinXP last year but shrugged it off as configuration or something. But now it's back with a vengeance.

Is this a Unity issue? The only way I can see this as a "configuration issue" is if something in the project was causing the solution to get generated incorrectly (er, but only on Win7-64 bit machines). Anyone else seeing this problem?

Please make sure that all 64bit Windows 7 machines have this hotfix applied. There is a download link at the top.

I'm seeing this on Mac OSX as well (snow leopard)

I have a large number of assets/source files and when I double click the file on unity (or if I double click an error in the debugger) it switches to MonoDevelop which can take up to 5 minutes to respond.

I'm scripting in C#.