The Situation: Spaceships take over our airspace and destroy entire cities in the 1996 blockbuster, Independence Day. Their plan: to destroy our planet. Everything seems lost in the first days of July, until...
The Solution: Our president inspires his fellow countrymen and they lead an assault on the alien visitors - an operation launched (unsurprisingly) on Independence Day. One man's self-sacrifice helps destroy the main ship, but the way that we ultimately save the Earth is by uploading a virus into an alien computer and weakening their defenses.
World-saving advice: Computer viruses can be good things. Sure, they can mess up your day at work - but they can also weaken alien spacecraft. You probably didn't know that, did you?