I see this too whenever I sleep the guest. I suspect it's due to the limited nature of support.
Ding ding ding, we have a winner..
Since there is not a full VMware Tools integration in the guest, there's nothing in the VM to synchronize time with the host and to recognize that the hypervisor has suspended and resumed the VM or the host has gone to sleep. The only thing that the guest can do is to synchronize with an external time source (through the NTP protocol, for example). That automatic sync only happens at VM boot and at intervals defined by Windows.
For the time being, you'll have to sync the time manually through the Windows Settings panel upon resume of a suspended VM or wake-up of the host.
- Paul (Technogeezer) Editor of the Unofficial Fusion Companion Guides