FF XI freezes and computer reboots after 5 minutes.Follow

All right... here's my problem, I'll just re-post the summary I posted on my LS forums, and then go into a few more details:

Before: The game would freeze up, most notably in areas of high congestion, when certain effects went off, opening up my menu, etc. It seemed to be a problem with the graphics card since it was graphic related most of the time. The freezing would last 5 - 10 seconds, then normal game play would continue. The next time I logged on, it froze each and everytime I tried to load the title screen, and then there would be graphical glitches when it resumed.

After: So I get my graphics card in... everything runs smoothly, my computer no longer sounds like it's shrieking. Every thing is nice, calm, smooth, and quiet. FF XI runs infinitely better, I'm in love with the graphics card. I run around Al Zahbi with my new found love. Then, it happens, in the middle of a /tell, the game freezes, except this time... the entire computer restarts rather than continuing game play. I get nervous, try again... 5 minutes into playing, the game freezes again. It won't unlock so I try ctrl+alt+delete. No good. I try alt+tab. No good there either. I press (not hold) the power button and the entire computer shuts down. I get agitated and decide I'll do the quick 2 minute run to the AH, throw my Gold Ores up on auction, and run back to my MH to log off. Sadly, I freeze in the middle of the square, with the same deal except I actually had to hold the power button this time.

A few things to note: My computer only freezes when I'm in FF XI. Playonline can run forever no problem, same with AOL and everything else.

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Alright, since then I have done the following without any change in what happened:

1) Updated Norton, and did a fresh Spyware/Adware/Virus scan. Absolutly nothing, and my computer hasn't had one instance of any of those yet.

2) Updated the graphics card. Problems with that were detailed above.

3) Cleaned out the computer with a Can of Air. It wasn't too dusty, but I thought it couldn't hurt. It didn't help either.

4) Because I was getting desperate, I called Playonline support. They recommended me to AOL support because of the nature of my problem. Nothing they recommended helped.

5) Replaced my Power Supply. My friend said he had the same problem and replacing his power supply did the trick. Didn't help me at all either.

6) Checked for corrupted Playonline or FF XI files, again, no problems there, so it obviously didn't fix the problem.

7) Disabled Norton Anti-virus, and tried playing. Still the same problem.

8) Uninstalled and reinstalled my AOL software. No change there either.

At this point, the only two solutions I can see would be reinstalling my FF XI, or well, reformatting my computer and hoping for the best. I would much rather not do either of those two as I have Dial-Up, and well, no one ever really wants to reinstall everything after reformatting. I checked the other thread on here that seemed to have the same problem I did, with what many people have suggested the problem could be, over heating. I'm no expert on computers (obviously) but I put my hand near each of the three vents on my computer, and other than slightly warm air coming out of the power supply, the other two were fairly cool. It doesn't seem as though my computer would be over heating with those symptoms.

I'm honestly running out of ideas. I've asked many people's opinions, and no suggestions have seemed to work so far. I would greatly appreciate it if any one has had previous experience with this, and how to fix it, or any other ideas that I havn't tried yet.

Thanks again!