Windows Vista is notorious in bugging you for slighest and minutest of reason it thinks may harm your computer. If you want to change some system setting or want to install a small program, a popup window always appears from nowhere and asks you for your permission. It think that some unknown person or virus or bot may be doing these thing to harm your computer. Most of the time, it is highly irrtating to a genuine user.
You can turn off user accounts control very easily. Simply click on Start Menu and open Control Panel by clicking on it. Further, on control panel, click on User account. You will see an entry named - Turn User account control on or off. Click on it and in the selection window that appears, remove the check mark on Use User Account Control (UAC) to help protect your computer. User Account control will never bother you again.
But, beware, this setting may actually harm your computer if your computer is infected with any kind of viruses, worms, trojen etc.