This may be worth trying.
In your home directory there is a tremulous (maybe .tremulous) directory. Not the one in C:\Program Files, but in C:\Documents and Settings\(your username)\ search for it, its in Application Settings or some such.
I forget precisely where (perhaps someone else here knows and can point us to it?). Look in this directory\base\ and find autoexec.cfg. Rename and/or delete that file. In fact, rename and/or delete that whole base directory. Again, NOT the one in C:\Program Files\, but the one in your home directory that holds your game settings. The autoexec.cfg file would survive a reinstall cause it is not with the program files, and is a settings file for your user.
(not a windows user, so forgive me for mangling its location

)