I keep getting the message thats in the subject header when I try to join servers. What gives? I thought this was a free game
valid cd key isn't reaching GuidAuth Server
Same here, i thought i was the only one.
about 33% of the servers I attempt to join give me that msg.
This happens to me (Linux client) sometimes if I am trying to connect to a server in the middle of a map change.
I just hit reconnect on the dialog box and all is well. 
The command /pb_cdkeyreg will sometimes fix the problem (but at least for me, sometimes it seems to be a while before the server responds).
hmmm that /pb_cdkeyreg helped a little. but there are still servers that give me that message.
anyone have more suggestions?
coincidentally… When I play vanilla RtCW, when I join games (Awaiting Challenge screen) I get the message “CLIENT UNAVAIL TO AUTH” or something like that. It won’t let me join the game, but after about 6 counts, the message goes away and I can join the server.
Is there a gereric ET error message site as i usually get
“CLIENT UNAVAIL TO AUTH”
and the GUID error
and my mate gets
maxpackets = some number
on loads of different servers
There are a few things that will cause this. Basically, they come down to two scenarios (the server you are on isn’t getting the auth, or the master server is too busy) and your only option is to retry the connection. Make sure you’re not contributing to the problem by choking your own connection, and shut down any apps that are eating your bandwidth. Likewise, only play on servers that you can get a decent connection. You might get a sweet ping to some 40 player Aussie server from Florida, but it probably won’t last once you start slamming a bunch of gameupdate packets through it. =)