Screen Freezes First my screen was freezing. Now not only does the screen freezes but it makes a grinding noise like its chewing up the game disc. I think I have a serious problem.

its just the cd.. the psp is ok but not the game

Possibly the disk, you need to clean it with disk cleaner.
If the trouble still persist, it's the lens problem.

Open the case, then the mechanical case, after you see the lens, use a soft cotton buds, then put it in alcohol, then rub the lens firmly.
After that rub again with cotton buds without the alcohol, that should fix the problem.

Well your disc is officially garbage because it's scratched for sure. Don't bother trying to fix your game disc. Do what I did. Go to sellitbroken.com and sell your game to them. They will give you good money for it.

Try using a disc doctor on your game.

The graphics processor, and second graphics chip both require a reflow. A special BGA reflow 'heat' machine is required.

FixMyConsole

How can we fix this? or where can we take it to be fixed?

its possessed

Thats the lazer head getting too close to the dvd's, means that it either needs proper cleaning with a good quality dvd cleaning disk and solution, or needs to be replaced.

open it up and clean the leanse with cue tip lil rubbing alcohal

Are you getting an error on the screen?
Does it freeze on every game?
I would also contact the person who sold it to you...see when he bought it ..it may still be within a year...and covered by Nintendo. Hope this helps