After recently graduating college I decided to format my drive. This I've done several times in the past, but this was the first time in a year or so. So I picked up and moved back home with my computer in tow. I get home and begin the reformatting process which goes extrodinarily smooth. My computer runs absolutly great after I get all my major previously installed software reinstalled, and then it happens...a total lock-up: No mouse, no keyboard.... HDD light quits blinking wireless Linksys USB ethernet controller light shuts off Monitor continues to display All fans continue to run(don't think it's heat related) It hums like it did before the lock up. All this tends to happen when the computer is idle and unused after an hour or more, but the lock-up has occured while in use and sooner than 1 hours time. No blue screen of death or weird computer antics its just a total stoppage. No flickering, grinding or anything else out of the ordinary. What I have done: I have 2 hard drives about 2 years old each (200Gb Maxtor, 160 Seagate) both ATA100 maybe 133 I can't remember. Anyway, I was sure it was one of my hard drives. So I tested both; unhooking one, resetting jumpers and cables, reformatting, and testing. I did that with both. No luck. Still determined it was my hard drives I went and bought a cheapy 80gb Western Digital and tried it. Again no luck. So I'm guessing it has nothing to do with the drives. Next... I was determined it was the memory (NOTE: I built this computer a few years ago, so don't laugh at how crappy it all is). I have 3 sticks, mix and match brands, of 256MB random DDR 2100, 256MB random DDR 2700, and 512MB Kingston DDR 3300)...I know I know this isn't the best use of resources but it's what I did at the time and it's worked for me until now. Anyway I tested each stick basically the same way I tested the hard drive and NO LUCK. I have a new stick in the mail, but I can't imagine that all three would be faulty. So that's what I've done so far and next to check would be the processor or motherboard... This is what I don't get... Why would my machine perform a perfect freeze after so much time has passed between start up and freeze time... This, in my mind, would rule out Software or Driver issues and maybe even processor or motherboard issues. Moving to an older house using an older power strip and possibly a more unstable electrical output I guess could cause my power supply jump and lock up my pc, but I'm thinking that is a little too far fetched. And yes I've tried disabling all of my screensavers, power shtuff and performed disk checking. It's not a huge pain in my neck because I can finish most of my work before a lock up and it runs great, but if I try to do a long download or I just want my computer to be on when I get back after an hour or so is when it gets annoying. any ideas? Some specs: AMD 1800+ biostar - can't remember...but it has AGP 8x and USB 2.0 among other standard features. 1GB random memory DDR2100 Nvid Gf fx5200 200gb maxtor 160gb seagate standard NIC card Linksys USB wireless receiver 802...g I'm running the same software I ran before the format. XP pro all windows default drivers except for linksys usb receiver THANKS FOR ALL YOUR HELP and sorry for the long post and horrible spelling.