Media Player problems on 6260

I'm having problems playing mp3's using the Real player software on my 6260.
The tracks play, but every couple of seconds there is what I can only
describe as a "squeak" during playback like some kind of interference. It
happens when using speaker or headphones so I've ruled them out. I've got a
512mb card in the phone with a few different albums on and they're all the
same so I've also ruled out the mp3's, they also play fine on PC.

Any idea's or suggestions to a cure would be much appreciated as its slowly
driving me nuts.

Deano