Problems with USB Devices when running under VMWare
The Debug driver makes frequent requests over USB when the target is running. This can cause problems for VMWare, which can mistakenly optimize these accesses. The problem can manifest itself as various unexplained errors.
See this VMWare knowledge base article for information and a fix/workaround http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=774