Eric Siebert at Techtarget has a write up on Snaps ( part 3 ) titled Troubleshooting VMware snapshots
Virtualization administrators can use snapshots on VMware ESX to travel back in time and figure out what went wrong with their virtual machines (VMs). In part one of this series I discussed how to use VMware Snapshots. In part two I explained how to delete snapshots without wasting disk space. But what do you do when your snapshots start acting funny? In this tip, we’ll troubleshoot potential problems that may come up when using snapshots on ESX.
Eric, overviews ways to track snapshots, and provides some nice resources for trouble shooting, another nice read.