Machine Check Exception

[Eduardo M KALINOWSKI <ekalin@bol.com.br>]

Today, for the first time, I got this message during boot (just after
some messages from ohcihcd):

HARDWARE ERROR
CPU 0: Machine Check Exception:                                    4
Bank 4:  b200000000070f0f
TSC a38a02f0b
This is not a software problem!
Run through mcelog --ascii to decode and contact your hardware vendor
Kernel panic - not syncing: Machine check

Well, mcelog --ascii does not help much, to say the truth:
HARDWARE ERROR. This is *NOT* a software problem!
Please contact your hardware vendor
CPU 0 4 northbridge TSC a38a02f0b
  Northbridge Watchdog error
       bit57 = processor context corrupt
       bit61 = error uncorrected
  bus error 'generic participation, request timed out
      generic error mem transaction
      generic access, level generic'
STATUS b200000000070f0f MCGSTATUS 4

The processor is an Athlon 64 3000+, on a Asus K8U-X motherboard.

The error first appeared just after I plugged a USB webcam in my system.
However, both times resetting the system made it boot correctly.

So, how should that messages be interpreted?

-- 
Experience is the worst teacher.  It always gives the test first and
the instruction afterward.

Eduardo M KALINOWSKI
ekalin@bol.com.br
http://move.to/hpkb