This might be grasping at straws, but some of the earlier(?)
AMD 486 chips had a nasty L1 cache bug but if I remember correctly,
it mainly had to do with busmastering devices..
It's very possible you might be touching upon on that bug. How old
is the chip and what stepping and speed? I know that 586/133 chips don't
have those problems (well, unless of course, it is doing it on one of those ;-)
)
And this would make sense too if it were happening on the 486 since the
discussion seems to be pointing at faulty cache.
-- Which is worse: ignorance or apathy? Who knows? Who cares? Cherish the here and now. Have cool, will travel. The err of cool.