What's the UAC (User Account Control) and how can I control it?

Turn down UAC. Both Windows 7 and Windows Vista include a security function called User Account Control, which dims the screen and flashes a dialog box whenever you install an app or change your system settings. Though this arrangement can be useful for catching sneaky apps that are trying to install or change things without your knowledge, it can also be annoying. If you use Vista, grab TweakUAC to make it less annoying without turning it off. If you use Windows 7, the default settings aren't too bad, but I recommend that you go into the User Accounts control panel, click User Account Control settings, and change the setting to the third notch down, so UAC will still warn you but it won't dim the screen.