Game freezes, what causes it?

I'm not sure if you guys still remember my previous problem with my 3DS XL in 2 of my retail copy games, but just in case, here's the link:

http://techforums.nintendo.com/message/128740#128740

http://techforums.nintendo.com/message/129246#129246

Anyway, today, there has been a new discovery in my MH3U game. Not only that it causes a software restart error, but it now can also cause the console to freeze! It has sound and everything but the screen just freezes and you can't do anything about it unless pressing/holding the power button until it shuts down.

Now I'm sure that it REALLY is my 3DS XL thats broken or acting weird and with that being said, is there anyone here who knows the probable cause of this? Something like a hardware malfunction or a lose wire or something broken inside the motherboard of the unit? I just hope there are people out here who knows stuffs like these.

Thanks