It can be a port issue, if you have a router, you need to make sure the proper ports are open. The ports that should be open are;
UDP 27900
UDP 29900
TCP 80 - Client/Server Standard Port for GameSpy
TCP 29900
TCP 29901
TCP 29900 - Server Standard Port (29920)
UDP 27901 - Server Must be turned on in serversettings.con
UDP 27901 - Server Must be turned on in serversettings.con
UDP 27900
TCP 28910
TCP 4711
UDP 55123
UDP 55124
UDP 55125
UDP 1500-4999
UDP 16567
Yeah, I've had the same error before. If your internet crashes, the game automatically thinks you are still playing the game or on a server, so it says your CD Key is in use.
Congratulations on getting all the streaming servers, as a staff member of the [uKm] clan, I and other staff members along with the clan fully support the work that you do.
Great achievement, keep up the good work!