I operate the SafeSquid Appliance
http://vmware.com/appliances/directory/va/675813/
on an ESXi 4.1 host.
After taking a Snapshot while running (not reverting to one) the appliance did not boot anymore (Grub Error 25).
I installed a fresh copy of the appliance, after the initial setup I took a snapshot of the powered down machine and again the same boot problem occured.
Any idea how taking a snapshot can corrupt the VM?