Windows 7: sound drops

Any music I'm playing (in WMP, winamp or other app.) every now and then drops. It's like every 15-30 minutes. There seems to be a connection with opening webpages. When I use (rather than open) a new tab in either Chrome of IE8 it happens most of the time. I think there are other triggers as well causing these sound stops.



The strange thing is that I can reactivate sound by doing the sound test in the control panel. When I start the test it says the device it used by an other application. When I do the test anyway, sounds gets back to the point it stopped.

The drivers seem to be ok, there are no hardware conflicts. I use Windows 7, 32bits version, lenovo laptop t60, Logitech Z-5 usb speakers and ATI sound card x1400

Anybody ideas of solving this?