1.just disable error reporting.
(my comp->properties->advanced->error reporting .. ..its for xp should be same for vista)
(or you can disable it from Tune-UP utilities if you have)
2. See what's the error that is encountered.
(it will show the error and not 'Windows Explorer has stopped working")
3. Google the error ....(check Microsoft's site ....too...it works many a times) and find a solution
post the error here too so we can have a look.
also you should first have a look at this
Windows 7 64bit Ultimate - Explorer.exe Freeze (AppCrash) - Microsoft Answers
its solved by a registry tweak ...