Don’t know if you are on a PC or Mac. On a PC when clicking on the file you should be given the option to “open” or “save” the file. If you click open and the file extension is not associated in your computer with the program (in this case BIAB), the computer defaults to opening the file’s code in text form. That’s what occurred initially. Don’t understand why Firefox will open it and IE won’t! Can’t replicate the problem on my PC.
As far as saving MP3s, if you’re on a PC, try right clicking on the link with your mouse and “save as”, otherwise it will open up the file in whatever program is set up in your system as default to play MP3s. This varies greatly from user to user, as does the whole issue of downloading for PC, Mac, Ipad, Android tablets, mobile phones. Add to this the variety of browsers for each platform…