Hi,
Quick update:
Have discovered if I open say Windows Media Player and start to play a music track, pressing Fn+F8 / F9 / F10 work as they should. So I have sort of solved this.
However, I always thought that initially pressing those keys first, automatically launched my preferred media software. I could be wrong though as It's been a while since using the function keys in this way.
So, the only function key that doesn't work is still the 'Mute' key. I suspect this may have something to do with preinstalled Creative Soundblaster X-Fi MB software which I was unable to reinstall after the new OS install.
Dell were unable to give me an activation key for this software and wouldn't even send me a CD with it on. I believe there's a program called Volpanel.exe which loads at startup and I think the 'Mute' function key is somehow connected to that.
Thanks for all your help.
Rob