Yesterday, my computer [Windows XP Home, SP2, with all recommended updates through Friday, the 12th]would not boot into Windows except (1) in safe mode and (2) by using Norton GoBack to restore it (the registry?) to an earlier time. Without these steps, the black Windows startup screen appears, the horizontal green progress bar moves back and forth for a few minutes, and the computer restarts itself -- time after time.
Althougn the computer had started on Saturday afternoon without any apparent problem, and again later that day after I had downloaded and installed 3 updates indicated as urgent by Microsoft Update, it would not start on Sunday morning without resorting to options 1 & 2 mentioned above.
The most recent GoBack restore point that generates a successful Windows startup is Saturday morning. Nothing more recent will make Windows start successfully. Each time I use GoBack and return things to Saturday morning, I lose important files -- including the Outlook file. That meant that I lost several very important emails that I had sent and received on Sunday. Fortunately, GoBack has a tool that can recover files more recent than the restore point used and that saved my bacon.
I have scanned using Ad-Aware and it discovered something called "Alexa" and removed it: that didn't solve the mouse jumping problem. I have run Norton WinDoctor and it has fixed 2 categories of problems (it says): a couple of improper file extensions and a couple of ActiveX problems: that hasn't solved anything either. I have used Registry Mechanic 5.2.310 (the latest) and it claimed to fix several hundred problems -- without solving the ultimate ones.
I am now running a Norton AntiVirus scan (maybe it was silly to wait this long, but it takes several hours on my machine; I run a complete scan one night a week with up-to-date virus definitions; and I go for years -- truly -- without any infections) At this point, it has scanned about 600,000 files (out of about a million) without discovering any "threats."
I have made regular backups using BackUpMyPC. The most recent one was yesterday morning, so I could use that path to recover important data, if necessary, up to that point, but I don't think I could trust the regestry files that it backed up -- they would be the same corrupt ones that seem to be plaguing me now, wouldn't they?
Any help would be appreciated. I would be happy to provide any additional information.