Yeah it does seem to happen randomly. Which is why I have disabled the SLI memory setting. What ram were you using on your board?
It was 2 sticks (1 gig each) of OCZ FlexXLC (PC2-9200).
I'm currently waiting for the P24 BIOS as I've got only basic settings on the board and no USB at all. If that doesn't work I'm hopefully going to try a Striker (and probably get another load of problems!