Im certain that people in this thread are having different failure issues.
Some sound like PB / Firewall issues, some sound like hardware -
NachtJager - if RTCW used to but no longer works, Ill bet youre having a hardware failure or PB issues. Ill assume you disabled PB and joined non ET servers to eliminate PB as the cause.
I have read/contributed to other threads in SD forums and seen heat be the cause of lock-ups. Ive also seen RAM go bad, and the PC runs fine until you try to do something different w/ it, like install and run a game.
Q3 engine is still used as a benchmark b/c it puts a thorough beating on hardware - CPU - memory subsystem - grfx cards. If you underclock a CPU and ET works, HEAT is your issue.
I also promise you that the game may freeze ( KB and mouse too) but the OS is still working fine under it, when grfx cards overheat. Get on roger wilco or voice com of choice, talk to someone while you join a server. When the games freezes and you can still talk on voice com, its your grfx card over heating.
CPU overheating will hard lock your PC.
RAM failure can show up in bizarre ways, and even go undetected until a program tries to write memory address lines to a particular physical space on your memory chips. PB runs resident in RAM, and does scan it for running cheats. It also scans the hard drive.
I overclock my athlon 1.7gig to 2.23gig, Im overclocking its clock speed and FSB speed, I have absolutely NO PROBS running ET.
Troubleshooting for heat can be as easy as taking cover off PC, you may need to have a table fan blowing air on it while you join a game and see if freeze issue comes back. If youre sitting infront of your PC and sweating, your room temp is too high for the PC to run ET w/out choking.
Id be happy to help anyone troubleshoot the issues they are having. You can PM me and Ill give you the IP for my Team Speak server so we can talk, or do it thru instant messaging.