PD9, Windows 8.1 upgrade disaster

So, i took Microsoft's advice and went to upgrade Parallels. Seemed to be going OK until suddenly the screen went black... every once in a while an icon would flicker into view and disappear again but that's about it, my install looks to have been blown out. Safe mode doesn't make any difference, although for some reason the Windows repair screen started up one time (and didn't help).

Any ideas, Parallels users? I sincerely don't want to have to do a reinstall since that might entail trying to convince Microsoft that I really do own the copy I paid for, that process is massively annoying.

 

Problem solved... I confused Parallels "Restore to Snapshot" with Windows 'revert to restore point', there being none of the former and one of the later... Duh.

So, reverted a la Microsoft, all is well, I'm going to do a snapshot before I try Parallels tools again.