dear all, we have here 2 servers as the following :- 1. Domian Controller Acting as Schema Master. 2. Exchange server 2003 as one & Only exchange server and it has all the mailbox of all the users. 3. 100 users have mailbox, and all the e-mails are stored on PST file on clients. due to some resons, we decide to formate the server of the exchange server it self. after we formate the server, we install the windows server 2003,with all the service pack. we did forest prep & domain Prep agian on the eexchange server , and when we trying to install the exchange server, i got this error message :- ============================================================================= THE COMPONENET " MICROSOFT EXCHANGE MESSAGING AND COLLABORATION SERVICES" CANNOT BE ASSIGNED THE ACTION " INSTALL " BECAUSE: - A SERVER OBJECT FOR THIS SERVER ( " HO-SRV-XCH ") ALREADY EXISTS IN THE ADMINISTRATIVE GORUP " FIRST ADMINISTRATIVE GROUP ". IF YOU ARE ATTEMPTING TO REOVER THIS SERVER, PLEASE RUN SETUP WITH THE DISASTER RECOVERY SWITCH, OTHER WISE YOU MUST FIRST REMOVE THIS SERVER OBJECT FROM THE ACTIVE DIRECTORY BY USING EXCHANGE SYSTEM MANAGER. ============================================================================= I DID NOT DO ANY THING ON THE DOMAIN CONTROLLER, THEN I CHANGE THE COMPUTER NAME, BUT I FOUND THAT THE SERVER NAME - OLD ONE - IS STILL APPEAR IN THE EXCHANGE SYSTEM MANAGER UNDER SERVERS. CAN ANY ONE PLEASE GUIDE ME WHAT CAN I DO IN ORDER TO SOLVE THIS ISSUE ?