Ill think it´s something about
No cd crack?
Seta cl_maxpackets to "15" or "30" lower.
Find this
For future reference:
1) Do not use a warez (aka illegal) copy of the game.
2) Do not use a non-CD hack of the game, even if it might be usefull and you do have the original game, no discussion.
3) Try changing the settings for MaxPackets in the config file.
4) Update or replace your network card.
The issue is with the server, conflicting maps/mods. If you remove all your mods/maps in your Main folder and you still get the issue, it's the server's problem
Soo reinstall for sure.
Here I found for ET some tip.
http://evilrtcw2.com/archive/index.php/t-10061.html
Soo hopefully something will help you!
Cheers....