I was getting a lot of these errors in the system event log on one of the servers we maintain.
This thread put me on the right track to resolving the problem, http://www.daniweb.com/forums/thread39730.html
1. Go to Start > Programs > Administrative Tools > Component Services
2. Expand the Component Services > Computers > My Computer > DCOM Config (I received an error at this point, I clicked no)
3. I then change the view to details which displayed the Application ID. I went thru until I found the application id that matched that in the event viewer.
4. Click on the Identity Tab. On that tab there is a "This user:" radio button which contains the username and password that my Component is using. Simply change the user login information, you may have to restart the machine.
Hope it helps 
UPDATE: Corrected a few typo’s.
Loading tweets...
1 ping
Tweets that mention The Ramberlings of a Geek… » DCOM got error “Logon failure: unknown user name or bad password.” -- Topsy.com
May 6, 2010 at 10:47 am (UTC 0)
[...] This post was mentioned on Twitter by Wayne T Taylor. Wayne T Taylor said: New blog post: http://tinyurl.com/2wghygs – DCOM got error “Logon failure: unknown user name or bad password.” #FB [...]