Lego Harry Potter: Years 1-4 Wii is Freezing?

The disc for the game is not scratched AT ALL. We checked it many times and we are sure that it is in very good condition. Every time we play the game, after about 5 or 10 minutes, it suddenly just freezes and continuously does this long "BEEP" sound that is so annoying! We made sure the disc was fine, the Wii is in good condition (we just bought it around 8 months ago) and we don't even use it too often because of homework, after-school activities, etc. But now it just keeps freezing and I would really like it to stop! Thank you so much for your help!