I had the same thing with VM Tools time sync... resync'd all my guests time backwards.. even though VMware SE's state that it only rolls forwards. Be carefull with your DC's !!
Did you have time sync turned on? Ourd synced when it was turned off, as well as going backwards when it's not meant to.
What guest OS(es)? We're running a combo of W2K8 64-bit and W2K3 64-bit, all re-synced when they shouldn't have.
Not going well with 3.5 Update 2 here... we're not in production so we didn't wait to upgrade, but so far have 3 major problems: today's licensing issue, this time sync issue, and a re-producible problem where W2K8 64-bit guest's get stuck at a black screen after sysprep'ing when HA is turned on (HA off = fine, HA on = black screen).