Computer Rebooting

Hi. I just got GW at christmas, worked well.
But when we put in new processor and motherboard it started to reboot randomly, mostly after I have played like 10mins, sometimes at login screen.
Someone have any advice to have this fixed? It's really annoying

system specs:
AMD athlon 2600+
ATI Radeon 9600
512mb RAM

Is the ram in the correct slot, Dimm 1, I believe.
Guild Wars was randomly closing out to my desktop or blue screening, but I was messing with the ram and realized I had my 2 512 sticks in the wrong slots. So I made it 1 and 2 instead of 3 and 2.
I haven't had a problem since.

Every other game work nice and I don't get any bluescreens,GW gets to desktop etc. My computer shuts down then I have to use the switch in back of the computer and restart it.

You say a new motherbard and processor was installed. Did you reformat and reinstall windows?

EDIT - just read you had no problems with other games....

The rebooting is almost guaranteed to be due to your processor overheating. Perhaps there's not good fit between the heatsink and the processor, or, more likely, the ventilation in the whole box needs improving.
There is also a possibility your computer resets due to issues with the power supply unit, but overheating processors is very common.

Maybe I should check how the processor fits there, I think ventilation is OK.
I'm also going to format windows, get rid of all crap

If you have like a small house fan, try putting it over your Processor/Motherboard etc on it's lightest setting, and just put it over it without the tower case on and see if it's run good.

My new Graphics Card (ATI Sapphire Radeon 9600 PRO Advantange) keeps making my PC reboot, but if I put my old 9250 in, works fine. So what I've done is, reset the Motherboard to factory default, (playing with jumpers on the motherboard in my tower - thanks to Tibs/Mog for that) and it's ran good. So I'm clearing all the crap of my PC, running my 9600 driver, THEN shutting off, and putting my new card in again.

Is the computer Beeping or Buzzing from inside the case before it shuts down? I would try trouble-shooting with the ram chips first before anything else. Pull them out...run with one in the #1 slot.....then run the other in the #3 slot. Then try running with one chip in the #2 slot then adding the other in the #4th slot. This is to see if one of the ram chips are faulty. There are memory tester programs out there...I just can't think of any right now....I am sure one of the build your own Guru's will post one or two of them on here.

Also try this with the extra fan blowing on the inside of your case....

Some computers like Dell's have LED lights on the back of the case that tell if something is wrong too. My Dell has 4 LED's that when everything is ok they are all green.

It does sound like a heat problem....or at least your computer is protecting it's self by shutting down.

EDIT: One thing I always do is to go to www.pcpitstop.com then run the tests there. You have to download an Active X file...then run the test...takes about 5-10 mins depending on your connection.