Ok I have installed a dozen or so Athlons and I have found that the lockups are mainly caused by two things:
Power supplies (the Fic board especially)
Memory (only use name brand)
I tried on my own system by first updated the power supply to an Antec 300 but no go still had lockups. Got rid of the BRAND NEW generic memory and replaced with Corsair PC133 and have been rock solid ever since
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"Cry havoc and let slip the dogs of war"