Can't unshare a shared drive in Windows Vista

I have a Vista PC on my network and 3 drives are shared. When I tryed to
unshare one of the drives I get the error msg:

Com Surrogate has Stopped working.
Problem Event name: APPCHASH, APP Name: Dllhost.exe, Fault Module Name
:ntshrui.dll, Exception Code: c0000005, Exception Offset: 00009f6d.

Can enyone help me find the cause of thie problem?

Thanks in advance.