I think it's a problem with your computer. I have the first generation Sprint-branded Centro, and it begins charging immediately when I plug it in to any USB port. I've tried it on my (Windows) desktop, (Mac) laptop, a USB AC adapter for an iPod, and even a powered USB hub that wasn't actually plugged into a computer. It worked every time. Either the specific port(s) you're using have something wrong with them, your phone has something wrong with it, or maybe if you have it from a different provider it's crippled (like how the AT&T Centro is EDGE, whereas the Sprint and Verizon models are 3G).