My wife's PC no longer has sound and videos play in slow motion.
The problem suddenly started about three months ago.

I have checked:
All Cable Connections OK
Speakers Switched On
Device Manager – No Problems
Ad-Aware sweep – Clear
Tasks – All unnecessary ones stopped/disabled

Clues:
BBC iPlayer Downloaded

Specification:
Vista Home
BitDefender Internet Security Suite
Media Players:
WMP
VLC

Help would be appreciated