My Ubuntu loaded Core i7 machine does exactly the same, not often, maybe a couple of times a month. Has been like it since new nearly 3 years ago. It is not a heat thing, the machine has been known to do it within moments of power up in the morning but can do it after running for many hours.
I assume that the "keep hitting f8" is a BIOS thing and so should be applicable to my system as well?
Rans6.......