mike, its a memory leak and more players in server, larger the memory grows, and it will keep growing until you reach an unstable size, or you run out of memory. What you can do until this server fix releases is have your server reboot every hour, set up a chron job in linux to do it... my server is windows so i set up a task with this command and in C:\WINDOWS\SYSTEM,
taskkill /fi "IMAGENAME eq MTAServer.exe" /F
need taskkill program from windows 2k3 resource kit to execute this command though....
you will need a loop script or have the server set up as a service for it to auto-reboot though
anyway thought i would post this for now until the server fix is out