Thanks for that Graham

I'm pretty confident the system isn't and has never had virus/spyware.
It has BitDef IS running permanently and I scan at least once a week with A squared/Ad-Aware/S&D...

The fault has been present for so long that I can rule out Sys Res - It would be more work getting the system back up to what it is today than finding a workaroud/alternative solution to the mp3 playback problem (which is after all confined to WMP 10).

From what I've read, the codecs are now built into the WMP install package. So if there is a corrupt file, I would have thought it would have been replaced by a clean version.

Thanks too Rharv but not sure what you mean by "the professional one".
Anyway will check out from the Control Panel and by looking into the System32 folder to see where we stand.

Cheers

Marc