DCOM error, event ID 10003

[Cyclone]

Can anyone tell me what cause this error msg ? I got 3 of them this morning.
Am I infected by msblaster worm or somebody is port scan my pc ?

Event Type: Error
Event Source: DCOM
Event Category: None
Event ID: 10003
Date: 8/20/2003
Time: 9:46:17 AM
User: N/A
Computer: XXXXXX
Description:
Access denied attempting to launch a DCOM Server using
DefaultLaunchPermssion. The server is:
{00020906-0000-0000-C000-000000000046}
The user is Unavailable/Unavailable, SID=Unavailable.

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http://go.microsoft.com/fwlink/events.asp.