I'm sorry for this bug. It doesn't occur every time and I wasn't able to reproduce it myself.
I will unlock the missions on your account.
Do you want to help me ? Add this to your command line when launching Quake2 : "+set wsrv_debug 1"
This command will generate a "wrsv.log" file in your Quake2 directory. If the problem occur, send the file by email to patmail at aftermoon.net
I'm sorry for the convenience :/
PS : if possible, try to use R1Q2, this engine has a lot of detailled error message when something unconventional occur.
http://www.r1ch.net/stuff/r1q2/