Explorer crashes because of a corrupt registry key

[alierror]

Hey there,
I have a problem with my windows,
When I right click on anything in desktop, explorer freezes, and then crashes.
I check the Registry using Tuneup and each time it reports that there are keys without any data.
The key which causes the problem is "*." key. It's address in Registry is:

HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.

So I try cleaning the problems with Tuneup, and it removes the key, and everything works fine after a restart.
But when I unplug my laptop (I guess it happens when I do it) again something creates that empty key.
Any Ideas?