OC resets to stock at AM autostartup

X48 DQ6, Q6600, 2x1gb Geil Evo One 1066, Zalman 600Watt, XFX GTX260, XP Pro SP3.
Mild OC, 333 w/8x=2664, 1:1 666 w/6 6 6 18. Very stable, gives 2 seconds faster on super pi and about 1gbs more bandwidth, 97ns latency on Sandra over stock.
But. Has just started resetting to default FSB and Memory settings after automatic (alarm) startups in the morning. Does not reset manual voltages, and doesn't happen at normal shutdown, standby, or restarts. Have q-flashed BIOS several times with no improvement. I have two different XP Pro installations on two different HDs that I can pick from the BIOS to boot, and both OSs exhibit the same behavior- which only confirms what I already knew: this has to be a BIOS problem. But why, with a fresh BIOS, does it continue?:confused
I need some ideas, I have run out; and just set my BIOS to the defaults for now.