What is wrong with my dslr? It's refusing to shoot video?

Okay, before you say that my sd card may not have enough battery, my SD card is 4GB, and I just shot a 6 minute video and it was 881 MB, so that is not the problem.

my nikon d3100 is supposed to shoot video in ten minute intervals, but it's not doing so, and it hasn't been for a while. I don't know why, does anyone know what might be the problem? I have tried resetting both the camera and reformatting my SD card, but nothing.

If the card is not a Class 10 card, thats your problem.

I agree with taylor, the problem is in the memory card. This is the diagnostic given by Nikon for this issue. You do need a class 6 and preferably class 10 card for video. The other thing is where did the card come from? There are many fake cards out there and slow writing speed is a characteristic of that. The problem is China is a communist country that does not recognize patents, copyrights and trademarks, therefore it is legal for factories there to imprint famous names like "sandisk" and "panasonic" on memory cards as long as they are not exported. But trading cities like Hong Kong are very porous and black market items get through customs regularly. Always know who you are buying from.