errorsound in mixvibes

Hello, i seem to have a rather strange problem,
everytime when i press one of the arrowkeys, the Enter key or click with my mouse in the mediabase or playlist, i get a sound out of my laptopspeakers (even when the sound is muted) i already muted all windows-sounds, but that didn't help either..
i'm using vista 32bit home premium (legal version)
the problem popped up without any specific changes..
i've tried updating stuff, but nothing helped so far..
solutions are more than welcome.
everytime when i press one of the arrowkeys, the Enter key or click with my mouse in the mediabase or playlist, i get a sound out of my laptopspeakers (even when the sound is muted) i already muted all windows-sounds, but that didn't help either..
i'm using vista 32bit home premium (legal version)
the problem popped up without any specific changes..
i've tried updating stuff, but nothing helped so far..
solutions are more than welcome.
Config Report: