Stop Error 0x000000B8

Can anyone tell me what this stop error means. I checked on Microsoft’s Knowledge Base, but it did no explain this error:

Stop 0x000000B8 (0x00000000 0x00000000 0x00000000 0x00000000)
A wait operation, attach process, or yeild was attempted from a DPC routine.
Begininng dump of physical memory

This is on a 2000 Professional. The machine is setup to dual boot W2k & W98. The W2k install is on its own drive. The error occurs when the machine is left alone. I have Zonealarm running. That is about all as this is a reletively new setup.