Please pardon my unfamiliarity with Protools, I actually use Apple Logic, but if Protools wil let you export to any other file formats like .WAV or .AIF you can always try a third party converter. I believe there's a free (or at least a demo) version of Switch which will allow you to convert nearly any audio file into any audio format.
I work in REAPER for that sort of thing, it will open any audio file I've come across and has no problem rendering to mp3.
Oh, and it's free, or more accurately, if you would like to support the good folks that develop it you can buy a license for around $40 and show your support, if not, they don't penalize you for it and you can continue to use it.
Just a thought.
Here's the link, it's a good program for audio
I use Switch when I need to convert something. I'm running a mac. And to be honest...I don't remember if it's free or not.....check it out. It's very easy to use.
I use Switch....not sure if it's free or not. But it's simple and will convert anything to anything.....Jon