The program should warn the user or even make it impossible to activate an encoding profile if the necessary encoding component (e.g. lame) is not installed on the computer. If this is not feasible then all activated profiles should appear in the drop down list. 

Other information:
I'm a somewhat computer savvy user but it cost me more than 15 minutes to find out that the codec was missing. I would prefer to run into an error message or something when starting the ripping operation rather than puzzle over the non-appearance of the profile.