http://www.hardwareanalysis.com/content/topic/31874/
There's a lot of answers there.... one that seemed promising was in the 2nd to last post:
I remembered I had been "playing" in the bios recently, possibly just before this error. I remember checking: "Configure for performance" Doh!!! I checked configure normal, no fixy. I reviewed every item, tried all the tricks in this thread (new to me by the way). no fixy.
Friend said: why don't you just reset your CMOS? Uh, what's a cmos.
CMOS reset resolved the issue - root cause of issue: over-confident husband in bios of machine.