Many thanks for all your replies!
Hi Guncrasher and Semp.
I rolled back the drivers, no change.
I reinstalled the drivers I got from the manufacturer with the PC, no change.
I reinstalled the lastest drivers for the sound card directly from Dell support, no change.
Hi Delirium,
Replying to your points:
1. Thanks for the info ..
2. The problem occurs on my headset and my desktop speakers, which pretty much means it's the soundcard.
3. I am not ruling out and will investigate further, as I also have an annoying buzzing noise on my phone.
Hi Nrshida,
Covered in point 2 above.
I think I'll try and rule out external interferance, and if it's still a problem I'll replace the sound card.
Thanks again,
Pandora