Replication Server System Database (RSSD) problems.
RSSD Deadlocks
Replication Server System Database (RSSD) deadlocks usually occur when commands for the RSSD are issued faster than the server can process them. Deadlocks may occur even on a fast machine and network when you run scripts that create, alter, or delete many subscriptions or replication objects.
RSSD Log Device Full
The Replication Server System Database (RSSD) log space has fallen critically low.