If you are getting errors in any of the replication agents (SQL 2000), and the GUI isn't giving you the details you need, turn on logging.
This is not an intuitive process, and when you are done you will want to make sure you turn it off or the log file can eventually fill up your drive given enough time.
To log an agent's activities, right-click on the Agent in Replication Monitor in Enterprise Manager. Select Agent Properties. You should get the Job info for the agent. Click the steps tab and Edit the "Run Agent" step.
You should see a command line with a bunch of parameters. Add these at the end:
-output c:\Agent_log.txt -outputverboselevel 3
Change the path and file name of the first one to an appropriate drive on the Distribution server.
The outputverboselevel parameter is documented as taking 0, 1 and 2 in Books Online. 3 is also an option and records everything.
If you wind up calling Microsoft SQL Server support, they will likely ask you for this info.
Good luck, and happy replicating!