Ok here's the deal.
I leave my main pc on all day, because I'm a power-wasteing bastard and because it's a web server! Anyway, a couple of times spread out over the last 3 months I have come home and my pc was OFF!

Symptoms:
- PC shuts down automatically. This is NOT hybernation, etc.
- Power light BLINKS
- All fans, hard drive are off. All is quiet!
- Hitting the power button does nothing
- Holding power button in for 5 seconds does NOT shut off machine to reboot.
- Must turn off power supply for over 5 seconds and turn back on to get power light to stop blinking and boot.
- System (Win2k sp2) has been rock solid for months. Haven't had any problems. Haven't installed any software in months.

Is this a power supply issue? A motherboard issue? Overheated processor?
<IMG SRC="smilies/confused.gif" border="0">

Specs:
Win2k Sp2
Athlon Thunderbird 850 (stock heatsink/fan)
Asus A7V
256mb PC133 (crucial, I think)
WinFast GeForce2 MX 32mb
20gig ATA/100 7200rpm
SBlive value
Kingston 10/100 nic
TDK velocity 10/12/40 cdrw
Memorex 48x cdrom
300watt ramdom power supply/case
3 large fans