Okay, here's the deal. I've had Vista for about a month or two, and I only started having this problem a few days after I got it... Anyway, at random times, my computer will just... stop. LEDs will freeze, sound halts... at one point, I thought this was because of overheating of my CPU or GPU in games, but then it started happening while doing anything, excluding doing nothing. This includes browsing the internet (or my hard-drives), gaming, etc. I guess this sounds like a RAM problem. Maybe it is... I remember having a similar problem, back when I had XP and a 450W power supply, and it WAS caused by the RAM. Whenever I put in a second gig of RAM, my computer would frequently lock up; but only when playing demanding games. There was also a loud... beeping tone, coming from my tower, I think. A constant sound, too. After I got a new 650W power supply (before upgrading to vista), everything seemed peachy with my secong gig of RAM. And I lived happily ever after. That is, until it started happening again, but this time with no sound (although now, it sometimes DOES have that sound). But here's the thing: it happens at completely random times. I can be playing a demanding game like the ETQW demo, or even the Crysis beta... and it might decide to just not lock up, even after hours of play. And sometimes it'll let me play for a staggering 5 minutes. I don't think it's overheating, because my CPU and GPU are only OCCASIONALLY hot when this happens. Same with my hard-drive. Any thoughts? Oh, and if it'd help at all, I'm using an 8800GTS 640MB. Two of my RAM sticks are Kingstons (I believe), not sure about the other two (512 sticks). I think they're a cheap brand, but I'm not sure.

The beeping MAY be an alarm telling you the computer is hot.

That occurred to me. But it last happened while I was browsing the internet, and when I restarted, my CPU temp was in the low 40's (Centigrade, of course).

It doesn't take long for an improperly cooled CPU to heatup or to cool down either. You may want to place a monitor on your desktop to see what is going on. Check in the BIOS under PC Health to see if an audable alarm is an option and if so, what is the current setting. Depending on which chipset is used on your MBoard you MAY even have a monitoering program on the MBoard CD.

It's an nForce chipset motherboard, one of the cheap kinds. I remember looking for one... Speedfan was one I tried, but that only supports Intel CPUs. It read my CPUs as being at a constant 127C. I'll check on the alarm thing, though.

Ram incompatibility could also cause these kind of problems. Asus K8V-X Athlon 64 2800 ATI AIW 9800 Pro 1Gig PC3200 WD 80 GIG LG DVD-RW XP Home Full time employee of Dharma. One of the "others".

Look on the MBoard CD for NV Monitor. I have it running in my tray. Came on the CD for my Foxxconn Winfast MB. Open all the folders on the CD by using Explore from My Computer.