We have been getting regular occurances of the following. A user leaves their client machine logged on. Their password expires while they are away (maybe over a weekend). We then see a huge number of 535 messages in the security log of their server quoting 'password has expired'. So many messages are generated that slow network links can be swamped, usually by connections to our PDC. We have checked Technet, Microsoft for this and have got registry fixes for our PDC as well as recommendations to install SP4 of Exchange 5.5. No joy. The problem only seems to occur from Outlook clients. Any suggestions?