The other day I was trying to add new items to my toolbox in Visual Studio 2008 and each time Visual Studio would close itself without reason. I tried the Reset Toolbox option which didn’t solve the problem.
I then tried running Visual Studio in safe mode by choosing run from the start menu and typing ‘devenv /safemode’. In safe mode I was able to get the Choose Items dialog so I just flicked through all the tabs to make sure it was working. I then closed Visual Studio and loaded it normally and everything worked as expected.
Not sure why it happened but this seemed to fix it