USB overdrawing power?

I have had my 13" MacBook for a WHILE, and this has never happened: I plugged my iPod Touch gen. 2 into my computer through my USB, hoping to sync my iPod with new music. I plugged my USB cord in my computer, WITHOUT MY IPOD PLUGGED ON THE OTHER END, and it came up with an error message saying something along the lines of "USB overdrawing power, will be deactivated." I then transferred the USB cord into my second USB port and it produced the same error message. What made this happen? Oddly enough, after blowing into my USB ports, it worked. Strange. Any advice or help will be greatly appreciated!

It sounds like it could be a bad USB cable. Perhaps internally shorted - that would definitely overdraw shutting down the port. Either that or it's a glitch with the USB controller. If it happens again, reset the PRAM.