I hate to ask the obvious but is the connector plugged all the way into the PC? You said that it worked 1 out of 4 times, or something to that effect. A connector that is just barely making contact could fool you (ask me how I know). Or is something else running in the background that might be taking up the sound, like listening to a radio station over the net?

Grasping at straws here, I know, but just asking....

Bob