Garageband doesn't cause this, it's just that opening an closing Garageband is the quickest way to reset your Audio MIDI setting s back to their defaults.
If you open up Audio MIDI Setup in the Utilities folder, is the Audio Output Format set to 44100.00Hz?
Also, check the Sound pane in System Preferences to make sure Play User Interface Sound Effects is checked and the Alert Volume isn't muted. 🙂