[txrx]

First off, do you have this problem before adding the new external drive?
Secondly i notice the only audio interface is with the mainboard itself. Some motherboard do have audio problem with certain audio application. ASIOFORALL seem to get quite a lot to work but then again it depend on what buffer rate you are running, not only mother board have static sound some sound card will also give static sound, best off is to see what the recommend brand to use and start off with that.