Then I'd probably try different versions of the program on both systems. If the settings don't display anything out of the ordinary I'd be trying to scrub all remnants of the program from the relevant systems so that I know it may not come down to a strange bug of some sort. If that's true I'd be trying to re-check all settings (which you've done).

How to find out which application uses speakers? How to determine which program is making a certain sound in windows 7?

In your case, I'd obviously be trying to ensure that that's the correct program that's causing the problem just to be certain that I'm not chasing my tail.