My phone is messed up... help!?

I try to make a video on my LG phone, [rumor] and i have my memory card inserted in it so i can record for up to an hour and i just got it yesterday. when i try to record a video, it always stops and says 'encoding fail' after a couple of minutes. I never know when it will say that because sometimes it says it after 3 minutes, or sometimes a minute. The longest video i made before that happened was 7 minutes. what does it mean and how do i prevent it?