We have a Symanetec Enterprise Firewall and mobile VPN users, everything was okay until we upgraded the IBM thinkpads to W2K, SEF Client 7.0 and Outlook 2K. Now the users can't send or receive attachments when connected to the VPN. We tried changing MTU size but that didn't work. They get message "Network problems are preventing connection to the Exchange Server computer." There's nothing in the firewall logs or the client logs. When attached to the LAN everything works fine.