I've only ever had the fan fire up on both my Pismo and Lombard when I had them sitting on a soft vinyl chair for a couple of hours watching a movie - it was pretty hot after that

Regarding the Lombard, the 400Mhz 1MB L2 cache CPUs are usually the ones that fail with faulty cache, I'd point it to that issue, more than overheating - they get warm with use, but not steamingly so!

JB