I swear - and I vehemently reserve the right to be wildly inaccurate, here - that I once owned a cheap-o laptop where only one of the USB ports supplied the "spec" amount of voltage and current (I want to say 5V and half an amp?) out of the port. A USB mouse'd require some power for LED illumination and what-not; and I wonder if the manufacturer cheaped out on the USB port power.
The other, and more likely scenario, like PandaBear said, is that something is disabled in BIOS or busted.