Hello,

> > This sounds really familiar.  I have seen something similar with my
> > Cyclades serial card.  I am convinced that interrupts get "lost".
> 
> Hmmm.  Think that this would also fix the on-board serial port issues 
> as well?

Hmm, I just saw the awacs* entry in my kernel config and the attached comment:
# awacs is disabled because on some systems--e.g., a 350MHz G4 GigE--
# it may generate interrupt storms, rendering the machine unusable.
# If you uncomment this, you'll also want to uncomment "audio* at awacs?"
# below.

This may be related too, if the interrupt code just stops handling certain IRQs the machine may become unusable.

have fun
Michael