Calm down. Would it kill you to loop memtest overnight and Prime95 SmallFFT's as opposed to the blend test? Also try lowering your LTD to 3x. It will not hurt your performance at all, because the hypertransport bus is nowhere near full. You can lower it to about 400mhz before you will begin to see a performance drop.
Its probably not the CPU though, my guess is its a software problem. Have you tried uninstalling/reinstalling aim? Or you could use a different client (I use trillian, its free and works with aim, icq, msn, yahoo, etc).