Can you get at the System Restore from Safe Mode?
I'll try it now. Be back.
OK, I'm back. I booted into Safe Mode and ran System Restore. First time, I went back to yesterday at noon. Rebooted, and the desktop wouldn't open with the Start menu and the taskbar showing, and no desktop icons would display. CNTL-ALT-DEL showed that a number of processes were running, but all I saw was the desktop's background, so I couldn't access anything.
So, I boted to Safe Mode again, and ran System Restore. I went back to 7/26/05. On reboot, the situation was the same as after the 1st System Restore.
So, I booted into Safe Mode again. This time, I ran msconfig as someone suggested in a FReepmail, and disabled all the Startup Items. Normal reboot and everything came up fine. However, I still have the same Shut Down problem, Zone Alarm Pro still keeps Thunderbird from opening, even though ZAP is set correctly to allow that, and I cannot open Internet Explorer, so I can't access Windows Update.
IOW, nothing has been resolved by using System Restore.
I am very close to an Install-in-place, as general_re suggested. I first need to peek at the back of the case and read my WinXP SN off the label. That isn't easy to do, physically, with the location of the case.