Apple changed the way Terminal windows are saved in the latest 10.5 upgrade.  If you get the “BG_Renderer_temp_file.term” couldn´t open because it is damaged error the fix is to go into the Settings tab in the Preferences in Terminal and select all the BG_Renderer_temp_file.term shells and hit the - (minus) button at the bottom to delete them. Things should start working again. Apparently Terminal stores all the shells now and it must reach some limit.  There is no other impact to Terminal’s performance.