Need computer wizzard...?Motherboard problem?

[OOZ662]

Just recently my computer did this for the second time in a long time, and I decided to post it for some help.

My computer sometimes, when idle, suddenly goes into what seems like a sleepmode(black screen) but will not respond to keyboard/mouse input. The catch is; it sends the fans into a crazy frenzy.  I think my case fan was built for 3500~4000 RPM at full speed but was easily doing 6000.

Since I downloaded/installed ZoneAlarm(freeware kind) last night, the computer has been randomly blakening the monitor and speeding up fans/HD when it's idle as if it were rebooting, but instantly recovers back to the desktop.

Is this a BIOS problem? I haven't had this computer a year yet, and sleepmode/screensaver/hibernation is disabled.

[Blooz]

Check for viruses!
Too hot?
Outside electrical interference?
Power supply problem?
Do you use a line conditioner?

Run a virus check in both normal and "safe" mode.

Check to make sure all the power connections are tight. Especially the one to the motherboard.

Check the temperature in the case. Heat does strange things to electronics.

Not a usual culprit but make sure you have no outside sources of electical or magnetic energy close to your computer. Flourecent lights, speakers, amplifiers, TV's...anything that has a big magnet or gives off lots of electical energy.

Maybe you have power spike problems. You'll need to check wether its from the outside to the computer or maybe a faulty power supply.

If it's the result of power fluctuations from outside you may need to add a line conditioner. This smooths the flow of electricity out before it gets to your machine.

If internal, may just need a new power supply.

[DipStick]

Also you might have your virus scan set to 'scan' while ss comes on. The 'fan' sound could be your cd spinning up for scan. ?!?!?!

[OOZ662]

I found out my computer was set to go into sleepmode every 15min (even though I never set it that way), so that will fix the small ones where it darkens/comes back, but I'm not sure about the complete freeze/freak out yet. Thanks for the help so far!