Hi. Thanks for the suggestion. I actually just switched the AV on the VM from Bitdefender to ESET Nod32 (for other reasons). But that didn't change this behavior. But, to make sure, I just disabled HIDS and real-time protection in ESET Nod32. Suspended the VM from Parallels (with Cmd-W). Resumed it. Tried to restart the VM from within Windows, and still got the same symptom. The VM hangs at the spinning blue "Restarting..." Windows dialog. I have to do a hard Reset from Parallels to get the VM back up.
This is a pretty significant problem. It means I have to shutdown the VM when I no longer need it, instead of just quickly suspending it -- or I won't be able to successfully restart it gracefully when the need to do that occurs.