Intensive processing = heat, especially if the house is being kept warm atm. Try cleaning your fans & cooling fins. Costs nothing & at worst eliminates overheating as the cause.
In general FF builds from about ~6-mos ago seem crashy on both xp, and multiple linux distros for me (though not causing BSDs or anything like that). Seems to correlate to javascripts. I switched to Chrome because of it.
Bloody thing did it again. Running memtest now, but apparently I'm meant to only have one stick in at a time to test them properly? Is there any point in letting it run with both sticks in or should I cancel it and restart?
If the test fails, then you'll know at least one is bad and should test them separately. Otherwise, they are both fine. IIRC correctly, if it is a memory issue it will likely transpire during a quick test anyway, and there's no real benefit to running the long test.