I strictly recommend you disable all non-Microsoft services (except VMware Converter services), reboot the server and try again... if you cannot do this now, try this on non business hours.
This recommendation you can found on VMware KB: Best practices for using and troubleshooting VMware Converter
To disable services, just do the following:
Run the System Configuration Utility
(msconfig)on the source server to reduce the number of services and applications running on startup, all software except for All Microsoft Services and VMware Converter Service. For more information, see http://kb.vmware.com/selfservice/search.do?cmd=displayKC&docType=kc&docTypeID=DT_KB_1_1&externalId=1004010Using the Windows System Configuration utility (1004010).