Problems with dual Athlons

[Donald B. Kinghorn]

... you have gotten some good advice ... I'll just through in my $.02 ...

We tried 20 of those boards and if I recall correctly 12 of them failed 
within a week ... we sent the rest back and shook our heads in disgust.

It's a bit of a nuisance but you might want to try swapping one of the boards 
that's giving you trouble with one that seems to be working OK. If the 
problem follows the board then you know where the problem is and it's time to 
get some new motherboards. If the problem remains with the machine then start 
suspecting power supply and memory.  

Probably the easiest thing to test first is memory ... run memtest86 on the 
machines that are giving you trouble. Let it run for several hours. Subtle 
memory errors can cause the behavior that you're seeing.

Best of luck sorting things out 
-Don