A customer had a workstation that was not getting connected to his SBS2003 server.
We could login from his worksation using a different username without any problem. We could login with his username at a different workstation with no problem. Initially I thought that his user profile was corrupted.
When I looked a little further I found that his user account was locked out at the server. If I reset the account - it would get locked out again immediately after he logged in. So, it was evident that something on his computer was causing just his account to get locked out.
Fortunately, my friend Mark C. called me to say he had thought of something that might be helpful. He told me about the Microsoft Account Lockout Tools - something I had never heard of. I used one of these tools to log all authentication traffic between the workstation and the server. After doing this - it was easy to find the process/services that were causing the problem. On reflection - it makes no sense to me that a service related to his Ricoh copier/printer/fax was the culprit - but when I disabled a couple services of Ricoh - the problem went away - and somewhat surprising also, none of the functionality of the Ricoh printer was lost.