Thanks for the replies.
I do have the VC++ packages installed & up to date AFAIK. I sometimes need these for the *very rare* gaming sessions
I am using Comodo CIS.
Normally whenever the PL updater comes up I run a CCleaner instance & turn off the CIS sandbox, before hitting 'update' to avoid any mess/interference.
In this case I had shut everything down, & cleaned up ready to power down the machine, & the updater came up just before I actually hit shutdown.
Technically there shouldn't have been anything much running, certainly nothing that wasn't running on the last update.
As far as I can tell PL is working OK, I've been running it for a few hours now & it seems to be fine. So a bit weird but relatively uneventful...