Trouble with some MP3: Pause/Play

One member mentioned on another thread that he had problems with the Pause/Play feature of the audio:

Maybe you didn’t realize that because he wrote on the “Ask your tutor” forum.

I’ve the same problem with some lessons from the “Listen to English” podcast. The player works for most of lessons but there are some lessons which causes problems. I have no idea what the difference is. An example is this lesson (“Are you worth it” from Listen to English): Login - LingQ
I can stop and pause but I cannot go forward and backward in the lesson in IE7.
If I pause with FF it starts always from the beginning.
I can see no difference of the mp3 files. Any ideas?