Here's the issue: F10 bios
I'd noticed that sometimes my bios would have multiple tries at initializing, that is, getting to the Megatrends splash screen and system beep.
Also, when the bios did finally succeeded at initializing [somtimes up tp 5 tries], pressing del would either do nothing and windows would boot, or it would bring up the tab menu
I then pulled the power from the computer, pressed the reset cmos button, rebooted and at the checksum screen loaded defaults and rebooted.
I was then able to do any number of boots into windows and restarts, or press del to enter setup and simply save and exit without changing anything and the system never failed once.
But, as soon as I disable Full Screen Logo Show [the only change], the bios would go into meltdown.
Of course, it's not too much of an issue, if it wants to show me it's pretty picture, fine - whatever keeps it happy
In fact, it's of no advantage to disabling it with this bios, as there's no boot info that gets hidden by the logo anyway.
It may however, be a pointer to a more sinister bug in the bios.
I'm yet to try the F11 bios.
edit: Almost forgot to add, that even after re-enabling the logo, the problems persisted. I had to reset cmos to kill the problem.