Slow Audio Playback

I have a Toshiba Tecra S1 with XP Pro. The laptop is
playing all audio too slowly. This includes MP3s on the
hard drive, CDs, DVDs & streaming, and it happens on
whatever media player I use. Strangely enough, it only
happens about 80% of the time, and occasionaly works OK.
Toshiba don't have a clue, and I have updated the sound
card drivers and de/reinstalled the media players, but it
still has the problem. Anyone got any ideas?

Thanks,

Nick.