When you shut down Windows Server 2003, you receive a stop error from the Mrxsmb.sys driver:

STOP 0x000000CE (parameter1, 0x00000000, parameter2, 0x00000000)
DRIVER_UNLOADED_WITHOUT_CANCELLING_PENDING_OPERATIONS

Where parameter1 and parameter2 are Mrxsmb.sys addresses.

This BSOD (Blue Screen Of Death) occurs if the Mrxsmb.sys driver is unloaded before it is fully shut down.

NOTE: Microsoft is aware of this behavior.