Okay so i have kingdom hearts 2 for the ps2 but it keeps freezing, will i lose my stuff if i get a new game?

well, every time i face that flying monster at mulan world and i beat it my screen goes completely white and i can't do anything except restart my machine. this also happens when i go inside winnie the pooh land. now i'v gotten really far in my game and it would be horrible to lose it so i was going to return the game because it obviously has a glitch and buy a new one...i saved everything on a memory card, but if i switch cds will all of my progress still be there and can i just pick up where i left off? please let me know because i don't want to have to start over =(