We are in the process of tracking down and fixing issues that can lead to a server crashing. This includes servers halting with z_Malloc errors due to a memory leak and access violations following multiple msg_Overflow messages in the log file.
We are currently testing a patch on public servers at Splash Damage, id Software and Activision. Providing this patch remains stable, we hope to release it to Server Administrators within the coming week. This would be a server-only patch and would not need to be installed by players.
We'd like to say thank you for the continued support that we are receiving from Server Administrators in helping us track down this issue.