This is a new Event ID for Windows Server 2003 R2 SP1 found in a new DFS Replication log. Always backup the Dfs replicas before reconfiguring Dfs. Get users to log off first, particularly if Folder Redirection or Roaming Profiles are configured to use Dfs. Examine and compare the drive letter path for each Dfs replica using Windows Explorer. Look for any of these paths that are empty or do not match the other paths for the same replica. Also look for odd looking folders (e.g. folder names ending in "_NTFRS_xxxxxxxx", where "x" is a random hexadecimal number). Rebuild Dfs using Dfs Manager and restore missing files if necessary. Ensure that the right replica is selected as the primary source of the folder content.
If a file under a DFSR folder is open, the lock on that file prevents DFSR from replicating it. DFSR will check if the file has been closed every 15 minutes. If the file is still open during the following attempts, this event will be written to the event log. This is by design.