I had a similar problem with P5 and Photoshop! Temperature seemed to be ok, but I later found out it was not. Sensor on the Mainboard showed values about 10 less than real and the CPU vent sometimes stopped. Put enough vents in your case. See that cables are not blocking the airflow (put them to the side of the case). A case made of aluminium (e.g. Coolermaster) also helps. You could also try watercooling. I plan to set up a new system in January with double-core Athlon 64. This system definitely gets watercooling and a lot of memory (approx. 4 Gigs)