It happened a few times before and it happend again. This first time when it happen to Visual Studio 2008 sp1. When I tried to choose items in Visual Studio toolbox, Visual Studio crashes. I tried usual cure:
In this case you need to back up all your settings and then restore them. Usually it helps, but not this time. Ofcourse I tried right click on toolbox and do:
As usual it didn't help. Finally I found solution. You need to run Visual Studio in safe mode.
Then try to do Choose Items in safe mode. Click on each tab. Press ok on any errors and you are done.