Hi People, About a month ago one of our customers started having problems with remote terminal server users dropping off and not being able to reconnect, but local users could still connect and work without problems. The problem slowly became more severe, despite the fact the the terminal server wasn't heavily loaded. Tried upgrading to Windows 2003 SP1 and the problem became even worse. Turns out to have been an MTU size issue (with XDSL connections) induced by MSO5-019 and made worse by Windows 2003 SP1. After a period of time the server/client thinks the remote host is unavailable due to retransmissions and timeouts. Microsoft have released a new hotfix to fix the problem. What they don't mention is that it doesn't install on a server with Windows 2003 SP1. Had get another version that was compatible with 2003 SP1. Anyway, the article: KB Article 898060 Note that the Post SP1 hotfix is different to the one offered to fix the problem. Installing security update MS05-019 or Windows Server 2003 Service Pack 1 may cause network connectivity between clients and servers to fail Network connectivity between clients and servers may fail. This failure occurs after the installation of either security update MS05-019 or Microsoft Windows Server 2003 Service Pack 1 (SP1). Any one or more of the following symptoms may occur: • Inability to connect to terminal servers or to file share access. • Failure of domain controller replication across WAN links. • Inability of Microsoft Exchange servers to connect to domain controllers. These symptoms are more likely to occur in WAN and LAN scenarios. These scenarios typically exist where routers and data-link level protocols that have different Maximum Transmission Units (MTUs) are used across the network. In this scenario, the sending host can receive several Internet Control Message Protocol (ICMP) destination unreachable messages that have MTU updates for a destination. These symptoms are most likely to occur if the following conditions are true: 1. During the PathMTUDiscovery process, several routers on the route to the destination send MTU updates to the source host. One of the possible reasons for this could be that source and destination hosts are in different WAN segments. Additionally, these segments are connected through a tunnel with a small MTU. 2. Network load balancing, dynamic routing, or both are used. In this scenario, there are several possible routes to a destination that has MTUs that are different from the MTU of the sending subnet and that are different from each other. Therefore, changing the route of IP packets over time can produce several MTU updates for the destination address regards, Rick Ulrich Mack Volante Systems