So my computer has recently randomely shutting off.  Before it was only while i played a certain video game. and now it occurs even when im not playing the video game. And this is a recent thing. What will happen is the screen just freezes up but my mouse can move around on the bottem part of the screen but wont be able to click on anything.
 
so i turn off my computer, when i turn it back on, it will simply be at the loading windows xp screen forever. it wont load up. so i turn off my compute for approx 10-12 hours, then i will turn it on and it works just fine, until i play my computer for a while, then it happens again. What could this be?

Hmm... Based on my previos experiences with such annoying probs, it must be the HDD... Open up the case and try to listen for "clicks" from your hard-drive... Try using different ram to eliminate possibility of faulty ram too... But, in all likely hood, its the HDD..

Was this a pre-built system or one you built?
What's the system spec?
How long has it been running?
What games cause the freez?
 
The problem could be caused by heat, bad PSU, failing RAM, graphics card etc. etc.
If it was the HD I'd expect a Check Disk to report problems, have you tried a Check Disk?

System specs, age of computer, etc would be nice.

I built this system. The system is a 6600 core2 duo proc. EVGA  680i mobo. 320GB seagate HD. 8800GTS 640 MB GPU. and a 700W OCZ PSU.
 
it freezed first when i was running counter strike source. and ive checked the heat of my processer and stuff after it has froze, and it seemed normal. how do i check disk?

In Vista in the start menu search field type chkdsk and run that. In XP click on run then type chkdsk. However you should tell it to run on reboot because then it can check the entire hard drive.

I suspect a heat problem.   You have some hot components.  To check on case cooling, open the side doors and direct a small house fan at the innards.  See if the problem goes away.   If it does, then we look to cooling solutions.  If you have fan filters, are they clean??
 

I dont think it is a heat problem. After it freezes while im ingame...i go straight to system moniter. and the heat on all my components are normal.

I was having similar problems which grew into random blue screens and I discovered it was my RAM which was bad.  Download Ultimate Boot CD and run tests on different parts to try and narrow down the problem.
 
http://www.ultimatebootcd.com/

I tried the ultimatebootcd thing. I also used a seagate program to check my hard drive, and it said it passed. My RAM passed but is there anyway to test your GPU?  
 
also ive had a long standing problem with my mother board 680i EVGA. Ive had to RMA it 3 times. could that be shutting my computer down while playing a video game?

In my experience, several people are thinking the same thing.
It's either a bad drive (check your connections as well, you could simply have a lose cable) or overheating.  
If it is a bad drive, troubleshooting software most of the time won't find the problem in the early stages when it is very intermitent. It will only show up later as the drive regresses.
Definetly do what someone else suggested. Take the side off the case and place it close enough to you to hear the drives, and listen for any clicking or humming, or buzzing sounds at about the time the thing locks up.

hmm ill have to try that.

So i took a listen to the hard drive after my comp did the freezing thing, and there was nothing suspicious about the sound. I was thinking it could be the video card, but does the video card have any effect on my OS loading up?

enigma322,
I had a problem like this with my old gpu(firegl x1) it ran very hot and it would constantly hang.  
When this hang occurred, I could move the mouse for a bit before the system would wither reboot or the graphics would fallback to what I can only describe as a "safemode" where the resolution is set to the most basic mode along with color depth and I got a prompt to reboot to restore normal operation.
 
I fixed this problem by installing a Zalman vga cooler on this card.
Problems like these could also occur due to a graphics driver issue, I recommend that you try installing the latest drivers(or try the previous version if you already have the latest). Also if you have a spare graphics(or can borrow one from a friend) card you can try running it on that to eliminate graphics as the culprit.
 
Your situation does not sound like HDD problems I have had in the past.  
When I had my first HDD failure the system would lock up when opening a file on the failing HDD, it was my data drive so it was not accessed when doing any tasks that did not involve files stored on it. Because of that the system was stable until I tried to access files on that one drive, when I did that I could hear this really nasty clicking sound.
*EDIT*
I recently had a problem with one of my SATA cables, the one connected to my Linux drive just suddenly failed after a reboot one day. In my case the drive was not recognized at all even in BIOS so I swapped the cable with a new one and then all was well, later I tested it on another drive just to make sure it was the cable. It's possible that your HDD cable could be going bad or just loose, someone else already mentioned this, but I just wanted to make sure you try that before putting the blame on anything else.

The fact that you can move the mouse at all rules out the possibility of the CPU, RAM, or PSU being bad. If it was the CPU or RAM you'd be greeted by a blue screen or a complete restart. PSU would definately restart you. I agree with the posts here I've had a similar problem where the video card overheats and I can't click on anything. Newer video cards tend to run extremely hot even with optimal cooling, so keep an eye on your GPU temps.
 
Edit:
Some cards get hot enough to burn you (90+ C   ) in their normal stock operation, so I wouldn't test it by using your fingers    

I would also try to download, burn and run a copy of memtest.
I think it's memtest.org
Extract it, burn it, boot it.
It will take a while (most likely, and I mean a couple hours) but it's the best memory checker out there I have ever heard of. It completes 8 different types of tests for reading and writing to indiviudal blocks of memory and will tell you how many errors there are.

Also, you might want to invest (hint:mininova) in a smart monitoring program such as ActiveSmart or HDD Life Pro. It'll read the s.m.a.r.t info off your HD and tell you if your drive is failing.

Don't be a tool, use the ones that are out there.

T

Mine is also doing something similar. I have switched out primary hard drive (it was bad, but not the cause) motherboard, processor, checked the memory, disconnected all fans and all harddrives and the second optical drive, switched power supply, took out all extra cards except wi-fi card.
My motherboard tells me it is a power problem with either the CPU or the videocard.
I ordered a new video card from Newegg a couple days ago.

You said you ruled out heat, memory, and hard drive.  Run a virus scan and also post your power supply specs.  Either of these things could cause the behavior you're describing.
 

I'd:
 
1.  Yank all cards / mem modules / cables and put them back in....to scrub off any dust or oxidation...clean contacts with contact cleaner or with iso alcohol if real ambitious.
2.  Blow out all areas of dust accumulation
3.  Run with side panel off and desk fan as was suggested.
 
Having something tell you the temps are OK doesn't mean that what it is telling you is right.  Asus's Smartdoctor tells you GPU temperatures on Asus cards.  You also might try Riva Tuner and GPUz
 
Spinrite is the best option for disk checking.

I didn't have time to read all the posts, but run a full scandisk w/ repair option and scan for bad sectors from a boot CD and memtest as well.  Those are two easy to do tests that require little effort

You only have the problem when gaming.   That points to a vga card issue. The possible reasons could be:
 
1)   VGA power problem.
     Your PSU is a good one, and should be sufficient.   Is the pci-e power properly connected?   Is there a 4 pin aux power connector on the mobo?  That supplies additional power to the pci slots, and needs to be connected to the psu for your 8800 to run at full loads.    
 
2)   VGA driver problem.    
    As mentioned before install the latest nvidia driver.   If you have already done so, try the latest beta driver.  
3)   VGA heat  problem.
     What case do you have?  How is the ventilation in your case?   Doors off, and a house fan is a good way to be certain that case cooling is not part of the problem.
 
4)   VGA card failure.
 
      Is the fan on the VGA card turning?   Can you feel hot air coming out the back, and the 5 slits in the card?
      Does the card need to be replaced?   Call vendor support.
 
One other possibility:   You have RMA's the mobo several times, that indicates to me that there is still some other problem lurking.   It is very unlikely that you would get three bad samples.  Contact EVGA support to try to resolve that issue.   It may be connected to your  gaming problem.