Sound distortion on Dell 1749 laptop

This is my first post on this forum and hope I am asking the question in the correct area. Have been using Serviio for quite some time and upgraded to the latest release. I have noticed that with Serviio running, when I use Skype or play any music, there is a distortion on my sound. I have tracked it down to the Serviio Service. Stop that and my audio is back to normal. it doesn't affect any audio Serviio is decoding , or indeed when playing a film from my Nas down to my laptop, then up again to my router and back down to a Sony bravia. My laptop is a Dell Studio 1749 running Win 7.

[zip]

That doesn't make any sense to me, why it's affect your audio. You could try to update your sound card drivers.