Cranio76

Hi folks!

I need help to troubleshoot this problem; I have a modest home recording audio workstation with a pair of cheap Behringer nearfield monitors and a Focusrite 6 USB soundcard.

Problem is that every computer activity seems to create a very annoying background noise, just as if it was some kind of ground isolation problem; I've already done a fair amount of searches and the majority of threads seems to deal with constant 50hz/60hz ground hum, but my kind of noise is different (resembles more like a random, non-constant old-style 56k modem chatter).

I get noises when:
- I move the mouse
- when there's a lot of screen activity (scrolling, moving windows)
- and when there's a lot of disk activity.

Furthermore:
- The soundcard is OK when I use it on my little netbook.
- No noise leaks through headphones

Any advice to possible causes would be really helpful, this noise makes mixing and using my nearfields very distracting. A partial solution is to lower the gain on my speakers to the minimum and boosting the audio card's output, but still I can't rid of the noise completely.

Thanks in advance

EDIT: it's my first time here, hope to be in the right forum section, if not, sorry and feel free to point me to the right one.