I shot some footage, but my computer told me that it cannot be played cause it was not formatted correctly. I shot from the Canon T2i. This was the first time my computer told me and it was playing just fine and then stopped, before it said that. It asked me if I wanted to format it properly. I clicked yes, and a warning popped up saying that doing so, would erase all the existing data. My friends who also own computers say they don't know how to fix this problem. Any ideas? Thanks.