We recently ran into a problem where a job in Backup Exec was failing when backing up the vmdk using Virtual Consolidated Backup (VCB).  Backup Exec was reporting the following error message: and reportint the following error message:  "The Virtual Machine resource is not responding."  After some trouble shooting and research we discovered an unallocated disk may cause Backup Exec to fail with that error when another allocated disk is beng backed up.  This turned out to be the problem in our case as we had an unallocated disk. [more]

Here is some more informatino about the issue from Symantec: http://www.symantec.com/business/support/index?page=content&id=TECH174797