Though Windows beeps helps to find out the problems easily, it irritates user pretty much. If you like to fix this beep, we have a cool registry editing way of turning them off.

♦Type "regedit" in Start Menu Search box and hit enter.
♦In the registry editor, go to the following key:
HKEY_CURRENT_USER\Control Panel\Sound
♦Right click on "Beep" string and modify "yes" as "no".
♦Close the registry editor and reboot the system.
♦Modify "no" to "yes" to revert back to default settings.
Source