why not try formating your memory stick?
Personally i dont think its the game problem.... why dont you
buy a new 1, or ask your friend to try it? Its unlikely the game
error, even if the game is faulty (which i often kenna also), it
just wont load the game and keep hang, but other data is still
intact.
Is your memory stick a OEM version?
To tell you the truth, I don't know.