I have recently installed Catz5 on my computer and the sound will not work. On checking the system device manager it shows a yellow question mark on the multimedia audio controller section. Any clues how to sort the problem out.

You need to reinstall your audio drivers.
Now which one you need depends on your computers hardware.
Best idea is to go to the computer manufactures site and get it there.

I have the best solution, go buy a new sound card =)