I would do like the above and also clean the laser. I am thinking more along the lines of rrod, seeming as the freezing. The only way the drive could freeze the game, would mean that it's struggling to read, and you would hear it. Best way to tell whether its the drive, or xbox is this. Get a spare drive, spoof with your key to a lite-on (if its not a lite-on already :P ) Then test the games. If there is no freezing, which I will bet 100% there will be, then its the drive. But its most likely the xbox.
There are a ton of rrod tutorials. I would go with lawdawgs method. Sorry I can't point you to the actual tut right now, but google it. Also, only try the xclamp mod. Don't do the towel trick, because that will just ruin it more.
As of right now, no one knows whether ms can tell. I mean it is an original game, and c4eva has announced the f/w can't be detected, but I know people that only played originals with a modded f/w and have been caught.
