Fourest:
I got it working again, I think it was a flaw in my code.
Good to hear that it's 'working' again. Although, the word 'working' that was used in the original post is kind of vague. The description of the problem wasn't very clear at all. Were you trying to say that if you begin with a bare unpowered arduino, and then you connect a USB cable to it, then your arduino would remain unpowered (ie. no power to it)? From the original post....nobody knows what you meant about 'working' or 'not working'......due to lack of details.