From my desktop running VNC Manager 3.6.15.0, I would connect to one of my servers. On the server I would run Microsoft Update. If that particular update(s) requires a reboot you get the window "restart now" or "restart later". I click on "restart now". At that point VNC Manager 3.6.14.0 freezes on my desktop. If I would choose "restart later" and restart the server normally VNC Manager would disconnect without freezing.Only after updating to 3.6.15.0 did I receive the "socket" error. Since upgrading to 3.6.15.0 I have only encountered one of my servers that required a reboot, so I'm not sure if it was coincidence or not. Prior to 3.6.15.0 beta, VNC Manager would freeze on my desktop and then I would kill the process and restart the application. Most of the time this happens on my LAN, btw I'm connected at gigabit speeds. I have a dozen or so servers locally it has happened on most of them.
The OS's that I connect to range from Windows 2000 Server, Windows XP SP2 and Windows Server 2003 R2 (it also froze before I upgraded my 2003 servers to R2). The VNC Server version installed is RealVNC 4.1.2
Hope this gives you a little more to work with.