I had Adobe and Norton nagging me to reboot, so I did that -- clicked Reboot from the Start button. Everything seemed pretty normal as it shut down and came back up, but once up a bunch of apps won't start.

The first one I noticed was Firefox. It would flash the disk light normally, but never appear on the screen. Then I tried to bring up an OpenOffice Calc window and same thing. I tried to bring up MS Word, and the splash screen appeared, but never the main screen, and the splash screen just sat there, with a swirly over it.

But I tried Solitaire, Notepad++, Paint, and several others, and they popped up just fine. And I'm typing this from IE 8, which, if anything, came up faster than usual.

When I try to open up "Network and Sharing Center" the window appears, but nothing appears in it, and eventually it's tagged "not responding". When I kill that window I get (after a delay) "Windows Explorer is not responding", and when I say "OK" the screen resets.

I tried rebooting again, and no joy -- same as before.

Have done nothing particularly strange on this box, and it's not generally at significant risk for malware. I haven't installed anything new other than the afore-mentioned updates.

One other thing: Several minutes after rebooting I get the message "Error: Unable to start Bluetooth Stack Service." The Bluetooth radio is turned on, and I rarely have anything Bluetooth attached, and I don't recall that I've ever seen this message before.

Added: Looking at Event Viewer, I'm getting a lot of "The description for Event ID 1 from source xxx cannot be found." Is there any significance to this?

Added: I'm looking at restoring from backup, but the procedure is, at best, unclear. Is it sufficient to restore from "Backup and Restore Center", or must I restore from the restore DVD first?