Camera freezed and wont turn off after 30 seconds of recording

The go pro works fine for about 30 seconds at which point the numbers on the screen disappear except a number two at the bottom left. The only way that I can reset the camera is to physically remove the battery. I've read some forums and it might be the battery but I don't want to buy a battery until I'm certain. I'm also using a micro SD card with an SD card adapter and that also may be the problem.