I also have an AMD processor. This appears to be the common link for all of us so I contacted AMD tech support about it. here's their reply...
Hello Graeme,
Hello Graeme,Thank you for contacting AMD's Technical Service Center.
The MCE at start up could mean the OS is loading up an AMD specific HAL
such as 3DNOW! Optimizations, or Power Management. If this is not
causing any system issues, I would not be concerned.
Regards,
Ryan Gardner
CPU Spe[censored]t
AMD
TSC