I am still having problems with exchange 5.5 running on NT4 server. The online defrag only appears to work on the c:\exchsrvr\DSADATA\dir.edb. I get 179 & 180 events but no other. The IS window is set for 12 hours every night although our backup window is 9 hrs. On Sat/Sun the IS window is 24 hrs but no online defrag of the private db occurs. We have has this server for about 4 years it is a Compaq ML530 twin Xeon 800 processors with 1GB RAM. It runs our exchange service and serves as a store for all of our data. Can anybody offer any advice on what to try next? Thanks