Trouble with pause/play function on itunes, acting as stop button

Hi everyone-

I was wondering if you might be able to help me out.

I've been doing transcripts for a year or so now, double-clicking the files from the downloads folder and having it open and start playing by itself, never had a problem- until last night.

I opened a talk in an mp3 format from the ICA's website (reputable, clean source, big art institution in london) and ever since, what happens is that when i press pause, either by the button on my keyboard, or by clicking on itunes with my mouse, it will either play back from 0.00 or from one other random point- which i had never paused it at. and this behaviour is now with all of my itunes content, not only the one recently downloaded mp3 file.

its incredibly frustrating as all the transcribing i do is for someone else, and this one is finally for me and my university dissertation- and i cant do it properly!!

and help is greatly appreciated.

Laura