I can't recall the exact issue I had a few months back but I had a backup failure on a customer site and to fix it I disabled VMware tools quiescence. From other various conversations over the past couple of years I know there are certain systems like Exchange or Domain Controllers where having one or other of these configured can cause issues.
I wish my memory was better.

If anyone has anything to chuck into the mix on this I would appreciate it.
Cheers
Hammy.