I have the same problem, and was about to start a new forum thread. Glad to see it's not just me.
Been happening for the same 4 PCs on my network since upgrading to 10.0.2505 (about 2 weeks). I usually get a notification every 2 days of this problem but are actually updating daily so cant be 21 days old.
I am finding 2505 to be very buggy with few problems for 2504. Maybe there are problems with upgrading from one version to the other that people aren't getting with fresh 2505 installs.

I really don't want to have to reinstall on all my machines again to fix this.