DFS ConflictAndDeleted not purging when quota limit reached

Hi,
We are running DFS on Windows Server 2003 R2 Standard Edition SP2 and
replicating from a Windows Server 2003 R2 Standard Edition SP1. I have found
that our ConflictAndDeleted folders are not performing their purge activities
when the high water mark of 90% of the quota is reached. When we set up the
replication we changed the default quota from 660MB to 23MB. However I have
found instances of the ConflictAndDeleted folder approx 16GB in size. Can
you advise if there are any logs that I can look at as to why this is failing
to purge itself?
Many Thanks,
Christine(sbs)