Why do you download OS X 10.8.3 when you already run it? And where do you download it from?
Have you looked at System Preferences > Energy Saver and set the sleep time to Never Sleep yet?
To edit your thread title to a descriptive one, to get a knowledgable audience and help making the thread easier to find for people looking for the same information, just click on the
button on the bottom right of your original post and then click the
Strange though, as a sleeping Mac can be awakened by a keyboard or mouse or trackpad, unless they are all Bluetooth devices and waking via Bluetooth devices has been disabled via System Preferences > Bluetooth > Advanced.