Yesterday, VMware posted a Knowledgebase Article about VMware Tools appearing to go off line after a VCB snapshot is taken. This issue occurs after applying the {font:Arial}{size:10pt}ESX350-200901401-SG {font}{size}hotfix.
The KB Article also says it can occur “for some time after the initial
snapshot” on unpatched hosts, but I have never seen it.

The work-arounds are simple:

1. restart the mgmt-vmware service (Make sure you don’t have VMs set to auto start)
2. Log In and log out of the VM, this will cause VMware Tools to kick itself in the pants.
3. Use the name or UUID lookup method instead of the ipaddr method.