from an Enemy Territory FAQ:
If you keep losing your settings, and/or notice sometimes that the the startup window shows (check.com crashed) beside the text, then it’s probably because of a error in the way ET handles mods. Basically each time you run ET it creates “profile.pid” in your profile folder, and sometimes this file doesnt get deleted when ET is closed, especially when you have been playing a mod. The result is ET detects the file and presumes that last time it crashed, so it resets most of the configuration to default settings.
See here if you want plenty of detail.
This means to fix it you can keep deleting the .pid file, but there’s also a simple preventative workaround, which is to make ET redo the settings again automatically (with the method given below, you need to set it up while ET is already setup properly). I much prefer the workaround.
When you have the game setup how you like it, open up ET/etmain/profiles/yourprofile/ and copy the file called “etconfig.cfg”. Rename the copy to “settings.cfg” and place in the “etmain” subfolder. Now, edit the autoexec.cfg file (notepad or preferably wordpad). If there isnt already this file in “etmain” then make a new .txt document using notepad and rename it to autoexec.cfg (make sure its not .txt.cfg). Now simply open it and enter “exec settings.cfg”, without any quotes.
When you run the game, it automatically runs autoexec.cfg, so everytime you run ET it should now reload all your settings from this file. However it’s important to note that if you make any changes to your game configuration you will have to set that in settings.cfg file aswell, or it may overwrite it next time you run ET. If you are comfortable with .cfg configuration files it may be better to simply put the settings you changed into settings.cfg. .