I had an issue with an XP workstation this week where a user could not connect to a certain dfs link in the dfs tree. The tree contained three root shares, one of those being the Apps folder. None of the PCs could map a network drive to the \\domain\Apps folder from explorer or using NET USE command. However, if the direct referral location was used (\\server\data\apps$), everything worked, so it wasn’t a permissions issue. After much troubleshooting and a couple reboots later, I came across an article regarding this issue (http://social.technet.microsoft.com/Forums/en-US/winserverfiles/thread/f64f87c2-76bd-4e0d-a34e-31fd5f321ba2/). The issue is with XP SP3, of which each computer that was having issues had installed. The issue results from a corrupted DFS link entry in AD. XP prior to SP3 would ignore it, but SP3 will not. The solution is to delete and recreate the DFS link and then purge the DFS mup cache on the client by using the following commands (dfsutil is part of windows 2k3 support tools) [more]

Dfsutil /pktflush

Dfsutil /PurgeMupCache