After I installed windows 2003 Server SP1, I lose the connectivity with user, The windows 2003 server is a domain controller and Exchange server and working fine from over five years without any problem like replicate with Primary domain controller . . . .etc , after I can't found a solution to solve this problem I uninstall SP1 and everything working fine now but I need to update SP1 to upgrade to Exchange 2007, I try to increase the MTU before uninstall and turn off the firewall but nothing happen. can you help to solve this problem Waiting your reply Ahmed Abdalla

Need more details about "lose the connectivity with user" and "try to increase the MTU before uninstall and turn off the firewall but nothing happen" You should be at service pack 2. Regards, Dave Patrick .... Microsoft Certified Professional -Microsoft MVP [Windows]