For what it's worth: I've got similar random crashed on my laptop (have had it for a while.) From this bug report responses I got the idea to try the -rt kernel (2.6.31-10-rt #153-Ubuntu SMP PREEMPT RT Tue Jan 12 11:01:03 UTC 2010 x86_64 GNU/Linux), and lo and behold, no more crashes. (I suspect this laptop also possibly has crash issues due to video driver issues, but suffice it to say that with the -rt kernel the machine has been rock solid even under intense load for several hours, which usually would've precipitated a crash.)
For what it's worth: I've got similar random crashed on my laptop (have had it for a while.) From this bug report responses I got the idea to try the -rt kernel (2.6.31-10-rt #153-Ubuntu SMP PREEMPT RT Tue Jan 12 11:01:03 UTC 2010 x86_64 GNU/Linux), and lo and behold, no more crashes. (I suspect this laptop also possibly has crash issues due to video driver issues, but suffice it to say that with the -rt kernel the machine has been rock solid even under intense load for several hours, which usually would've precipitated a crash.)
Do you need anything from me? (logs etc?)