We saw this same issue and it would happen repeatedly to the same VMs.
Ultimately, our issue was a CPU issue, not an issue with VMWare. The E5-26xx series CPUs exhibit a rare bug related to VT instructions and there was a BIOS update to resolve. In the case of an HP BL460c Gen8, the BIOS update to I31 2013.09.08 resolved the issue for us. I would assume all manufacturers using E5-26xx CPUs will be releasing similar updates.