I have a 5 year old computer and I've been having this strange issue lately. When I boot up my computer I find that my date & time is set back to 2001. That's not the strange part though. The strangeness shows up when I shut my computer down. It shuts down completely... for only 2 seconds, then it starts on its own.
I've researched and found that it had to with Bios and Cmos. I first tried flashing my bios and that didn't solve anything but taking out the cmos battery and puting it back in worked!
However the issue has come back to hunt me again. I used the same fix as before but it only worked temporarily. So my questions are;
1) Should I replace the CMOS battery?
2) Can I replace it with any 3V battery?
3) One time the issue occured right after a blackout that happened while my computer was on, does power shortages affect the Bios/Cmos?
4) Which one is better; leaving the computer unpluged or pluged while not in use?
That sounds exactly like the symptoms for the battery being dead.
Yes, any 3v battery will work, just make sure it matches the polarity.
A short could very easily affect the motherboard, but most high quality PSU's will protect against anything happening caused from a blackout. Common indicators of problems from a short is nothing happening. no lights, no fans, no beebs, just dead. Your problem sounds like the battery.
Plugged in is fine. There is no reason to unplug it. Leaving it plugged in will also increase the life of the PSU due to the capacitor's having a constant charge instead of constantly charging and draining.