I have one customer who, for some reason lately, is having VSS issues and I can't seem to figure out why. This environment consists of one ESXi host on which a recently virtualized SBS 2011 server resides, ESXi version is 5.1 U3, the server was virtualized back in July and since then its been running fine. Veeam is replicating the vm every two hours and backups are run once a day, nothing has changed except windows updates. A little less then a month ago the first issue occurred and it was a hung replication job, opened a case, determined to be VSS issue, rebooted guest everything was ok, except it occurred again about two weeks later at this time it was discovered that there were over 400 shadow copies on the guest, after deleting them and rebooting the guest we resumed working. This Friday Sept 23rd I noticed a hung replication job again, called and opened case #01090579 and again was told it was a VSS issue, although I uploaded the last 30 days worth of logs for the backup and replication job as one of the engineers asked to look at them. The replication job always hangs with the same errors message:
Unable to release guest:Error : Unfreeze error: [Cannot wait for m_FreezeFinishEvt: 
I have a couple of other customers running SBS 2011 in virtualized environments also and I checked their servers tonight, and ran Vss admin list shadows, they both had quite a few shadows going back to the beginning of this month, however when I ran the Vssadmin list writers, they both listed them right away. On my problem customers server, they have a few shadows too, but when I run the Vssadmin list writers command I always get the same message ' this may be delayed if a shadow copy is being prepared'
The only differences between my customers is ESXi versions and that one only has backups running once a day, the other has replications running just as often as my problem customer but no VSS issues.
I am not adverse to calling Microsoft at this point, just curious if anyone else out there in the community has had this issue that seems to have come out of the blue. I am getting tired of having to reboot my customers guest VM and they are getting frustrated too.