Why does my computer sometimes beep in Windows?

In Windows Vista, the System Beep is enabled by default. Every time you encounter an error or you click through menus of certain applications, you will hear a system beep. This may become quite annoying for some users.

To disable the beep, follow the steps below.

First, go to your desktop and right click on the My Computer icon. From the drop-down menu select Manage.
In the Computer Management window go to System Tools -> Device Manager. If UAC is turned on, you will need to make some additional confirmations in order to access the list of devices.
Now you will need to go to the View menu and select Show hidden devices.
If you return to the Device Manager you will see a category of devices called Non-Plug and Play Drivers. Expand that list and select the Beep, as shown in the screenshot below.
Right click on the Beep and select Properties.
In the Beep Properties window go to the Driver tab. From the Startup scroll down list, select Disabled and press OK.