Premirer 6.0 bussy audio problems

Hi all.

For some odd reason I am getting buzzing on the audio tracks when capturing. It sounds similar to a tape being off track. I get this problem from 2 cameras. Canon and Panasonic GS400. The fault seems to be coming from the pc, as when head phones are connected to the camera the buzzing is not there.

The camera is connected via a Dv cable direct to the capture card (Pinnicale).

PC spec. P4 2Ghz
512 Ram
3x 120GB HD.

I have disabled the virus checkers etc, pulled out router connection but still the problem persists.

Does anyone have any ideas what the problem is? Am I better off buying Avid instead?

Hope someone can help,

Cheers