It was reported by a local office technician that over the course of a few days several users were connecting to a site over the web that used Remote Desktop Connection to connect a remote desktop/terminal services session. Shortly after connecting, users complained the their session was being disconnected. The issue was initially troubleshot as possibly a local setting in the OS, such as the IE proxy or maybe the TMG firewall client, but switching to different proxy made no difference. It was then assumed that perhaps our network work was part of the problem. Port issue? Not likely, ports 443 and 3389 are too common and since the users were able to connect initially, this could be eliminated as the cause. Last, the remote site technical support was contacted and asked at what point inactive sessions were being dropped. The answer to that was 1 hour and so this, too, was eliminated as the cause.
Eventually, the issue made it my way, and the first thing I thought was that this was not specifically a “disconnect”. When I think disconnect, I’m thinking along the lines of excessive packet loss or corruption between the client and the server which results in a dropped connection. Another cause for a disconnected application could be that the client app or one of its components that handles the connection is crashing. To confirm my suspicion, I asked the local tech to provide me the name of one of the affected workstations. All the affected workstation were running Windows XP, which meant that if the RDP client was crashing, the post mortem debugger might be capturing this. I navigated across the network to \\computername\c$\Documents and Settings\All Users\Application Data\Microsoft\Dr Watson and saw a recent drwtsn32.log and user dump.