I know a little bit from doing some networking
1. The drivers for your USB ports probably need to be loaded, you can check by going to My computer, then right-click and go to manage and over to the side you should see a list of components that your computer has, scroll down to USB and if it has a yellow question mark then that could mean that your drivers are not install.
2. If you plug your USB and a popup comes up in the right hand corner of your computer, then click there to install the hardware.
3. If you have a duplicate USB port and you plug it in there also and it still doesn't work then its definately the drivers that need to be installed.
I don't think it's a problem with USB cord unless it's all frayed up. But as a last resort you can try that to see if that would solve the problem. When I had the same problem it was coming from my drivers being deleted and I had to re-install them.
Hope this info helps...Good Luck!