How can I make my MacBook Pro screws stop screwing around?
The first time you unscrew the screws on your computer, you'll notice there's some blue gunk around the threads.  That's Loctite.  It's essentially a sort of superglue for screws to help them stay in.  The glue adheres the threads to the casing, but isn't strong enough that a decent screwdriver and some wrist action can't break it.  I'd probably recommend finding an appropriate bottle of Loctite and then dabbing a bit on the screws and then screwing them back it.  That should keep the suckers from comin' back out. :)  I'm not sure about prices in Brazil, but in the US a bottle of Loctite (or something similar) should only cost you a few dollars.