Active Directory Replication Monitor errors

We have a weird issue. Not sure why this happens. We get this error between 2 servers.
All are windows 2003
Active Directory Replication Monitor
There was an error during queuing the synchronization. The error code was: ERROR_REPLICA_SYNC_FAILED_THE
REPLICATION OPERATION FAILED TO ALLOCATE MEMORY.

I have tried all means to fix. landed here on this site searching for some other issue and decided this is the best place to post as one of my other issue was fixed from solutions here.
Thank you
george
