We came across a Vista SP-1 workstation that threw this DCOM error hundreds of times every day:
DCOM 10009 MM/DD/YYYY HH:MM:SS AM 884
Event Details: DCOM was unable to communicate with the computer XXXXX.xxxxx.local using any of the configured protocols.
When we checked with MS PSS, they told us it's was a local firewall issue. Allowing Windows Remote Management through resolved the issue.