How are you adding this file to your project? Are you using Get Media/From Files and Folders?
Although Premiere Elements will work with MP3s, you'll get much better performance if you convert the file to a WAV using a program like the free audio editor Audacity.
Yes, get media from. I'm sure I've used it before... perhaps it was in Version 3 before I upgraded, but it doesn't work now for mp3 in version 9. I converted it to WMV or whatever the windows audio is and it worked fine. Just another quirk I gues.... The strangest one I've seen yet is no "back to start" button, have to use the HOME button on my numbers keyboard. Just glad I was able to find someone who suggested that.