HI all. I am new to this so please excuse any errors. I have a P4 3gig, 1gig ram, 256 graphics (or is it 512? Can't remember), 180 gig hard drive pc that I had custom built for me just over a year ago. Since I had it, I have had loads of problems with it. Most have been sorted out by the shop that built it for me (I have had to take it back 6 times in the past year) but this problem persists. Whenever I play a game (be it Rome Total War, Football Manager 2006 or Doom 3!), listen to music on WMP or iTunes, stay on net for a prolonged period of time, look at pictures or movies, then it freezes. I hear a couple of 'beeps' then it freezes. If I press reset, the PC just makes a long beep noise so I need to switch the power off from the back. This happens regularly. The last time I returned it they appeared to have fixed the problem. They said that it was a heat sink problem. Got it back from the shop and it appeared to be working perfectly, better than it has before. But low and behold, it problem has returned. My 1 year warranty has now ran out and I would like to attempt to fix it myself before going somewhere else and having to pay for it to be fixed. Does/has anyone here have/had the same problem and how did they fix it? Any help you give will be greatfully received.