Good to see other people still posting, maybe X38 is only dead for Intel.
BT, guess you're right, don't have much hope for new drivers or BIOS anymore.
tam, welcome back. I had the idea that this behaviour had been fixed in the past, guess not. I don't think I had this issue, not latelly at least. Power here doesn't go out that much, although not the cleanest. Still, last weekend there was some electric work being done and we lost power quite a few times, and for a long time. Still, the rig is running fine. I have problems with my Platinums though, errors come up while testing, guess it's RMA time.
Are you Ocing? Have you tried setting BIOS at defaults and see if it happens the same? Maybe also relaxing mem timings.
Mayve voltage usually is too low and the system (PSU) must shut down, if it's out of spec. Try reading voltage input with a multimeter, see if it's within the power company specification (plus minus limits of course). Maybe voltage is just to low to power your system.