Windows Won’t Shut Down

I have experienced the problem of Windows not shutting down a few times in the past, on machines ranging from 486 to Pentium 4, running Windows 98 to XP. When everything else failed, I used to just switch off the power, and it would shut down. It did corrupt the Windows files a bit or a lot, depending on my luck, but nothing a scandisk would not fix, and if it couldn’t, I could reinstall Windows again. When it happened yesterday, I tried “start – shut down – shut down” sequence four times. It was no good. The desktop just sat there, as peaceful as a monk. I did not feel like switching off the mains, because I was in the mood of being analytical and scientific. So I launched the Windows task Manager by pressing Ctrl-Alt-Delete keys together. There was no application running that was interfering with the shutdown process. I tried to shut down through the Windows task Manager menu command. The result was the same as after standard shutdown sequence. When it failed thrice, I wondered if there was a loop being executed indefinitely, so that Windows remained busy trying to shut down. So I looked at the processes being run in the Windows task Manager. Well, it was nothing like anything I had seen before. The processes were moving up and down the queue at a pace that would not let me click on any one process so that I could stop it. There was a “signal.exe” that I had never seen before. Before I could click on it to shut it down, it would move down and some other process would take its place. There was indeed a loop and there seemed to be no way of stopping it. It could have been a virus, though unlikely since my antivirus was updated and active. Then I had an idea. I launched the Windows System restore utility and restored the system to a date 2 days ago. It was successful. Then I tried the “start – shut down – shut down” sequence, and it worked! I hope someone out there finds this useful.