Invalid Handle on Login (latest Parallels, Windows 10, Sierra)

I had the same issue for several weeks which persisted after upgrades to High Sierra / Parallels 13. Reinstall of Parallels Tools, Windows restore, etc, did not work.
Per other users, the solution posted by MikeS14 on this thread worked for me:
https://forum.parallels.com/threads...r-freezing-task-scheduler-crash.340605/page-2

To summarize,
- Start Windows PowerShell or Command Prompt (once the start menu finally works) and type "regedit"
- Navigate to Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\Maintenance\State
- Under "ReportedState", change from 3 to 0
- Restart

This temporarily fixed the problem but the bad behavior came back several days later. I reapplied the fix and did various Windows updates (don't remember the exact order). The value of "ReportedState" now shows 1, "Control Panel"->"System and Security"->"Maintenance" section now allows "Start Maintenance", and things have been stable for a couple of weeks.

Per MikeS14 this is "at your own risk" and possible side effects are unknown, but the system is behaving for me now.

 

Sorry for the trouble, everyone. We're working with Microsoft to resolve this issue and will provide a fix from our side in a future update.
If you're affected by the issue, use workaround posted by jeffsorr/MikeS14: