Well, not quite, but our machine got trapped in an endless cycle of update / roll back / reboot / Windows not Genuine as described by another user here:
KB950582 killed my Vista machine It downloaded, restarted tried to install, shut down, said it was "improperly configured" and tried to roll itself
back. Rebooted and got the "Windows not genuine" screen. Don't bother going to the activation process. That didn't work.
Booted to safe mode got to a restore point. Restoring
brought things back to normal. Rebooting from last known good configuration did not work.
I put that update in the "Ignore" file.
Thanks a bunch, Microsoft. Warned Judy not to get a new machine with Vista because it's not stable yet. But she's banking on it being stable 2 years down the line... and in the meantime, supported by Microsoft longer than XP will be.
Anyway, the only reason I'm blogging this is in the mad hope that somebody will google this malevolent update before blindly installing it. BUT, of course, Vista will likely install it automatically, as it did on our system. It took a call to Dell tech support and turning off auto-updates to get the system even remotely useable again. And now that I've turned off auto-updates, of course, it warns me every 3 seconds because it's not secure.
If you've come here by googling Windows update KB950582, please feel free to stop by and read about my gardening and suppers!
Salmon with a bottle of General Tsao sauce - yummy
Rice pilaf with garden chard and lots of garlic to mask the chard taste - yummy
Garden green beans (a few)
Frozen peas (a lot)