Weird Vista 64 SP1 problem - Task Scheduler snap-in broken

It started with me running Firefox, which then promptly crashed when I tried
visiting one of my favourites. I tried this a few times and it would even
crash when trying to open a menu item. IE was fine however. I then found that
I could not get into Task Manger either. I checked in Services and half of the
Automatic ones were off! I restarted the machine and then the Aero desktop was
gone. The Themes service was not running. I started this and a few others that
weren't running and then found that the Task Scheduler MMC snap-in was broken.
And a few others as well. I ran SFC and that found no problems. I tried to do
a Sytem Restore but the program just generated an error message!!

After several restarts, and with a potential restore looming, the system
started working again. This brought back painful memories of when I first
bought Vista when it was released and back then I had it installed for a week
when the Task Scheduler service died and the advice on the MS forums was to
re-install........

Just to be on the safe side I went back to a restore point two days previously
but it does leave me a little concerned now.