microsoft visual studio has encountered a problem

you should have taken screen shot and posted here

 

from text only description it is difficult to understand

 

but I am telling you based on experience - this may happen because of memory issue,when your PC is low on memory and you try to open an asp.net form in design mode which has many controls on it then this may happen.

 

check your memory consumption, probably close other applications, or if still problem consists, work in "source" mode only, not "design" or "split", I never see the form in design mode in VS, I just run and see it in browser.