Weird... just opening it shouldn't have any effect.
Try the following guide: ( http://guvnr.com/pc/ubuntu-kill-system-beep/ )
-Go to System > Preferences > Sound
-Uncheck "Play alert sounds"
(you'll need to reboot to see if there are any changes)
If it doesn't work, go to Applications > Accessories > Console (or Terminal)
-add this to the end of the file and save
sudo gedit /etc/modprobe.d/blacklist.conf
-and add the same lines to the end of the file, save and reboot.
sudo gedit /etc/modprobe.d/alsa-base.conf
It should disable every kind of system beep in the computer.