uninstalled AVG and all of its components, as well as half a dozen other applications, games and utilities that I have either never used, or haven't used in years.
also reduced max texture size to 256 from 1024
played for a hour and a half or so last night, glitch free.
thought it was fixed, then the freezes started again. logged out, shut down, let computer cool for a while, then rebooted.
AMD software showed GPU temp at 35 deg C, so still cool. Game froze immediately after restarting and logging into arena.
"Strange things are afoot at the Circle K."