Replacing your USB port is nontrivial (effectively: get a new laptop), but if you hotplug in and out of it often, this (being screwed) is a real possibility.
Not every design has always properly buffered the port against ESD/etc. ABit in particular were peoned by this a few years back... it's *supposed* to be a hotpluggable interface, but Your Manufacturer May Vary.
As a quick test to see if ME is your trouble, you can burn a copy of Knoppix and see if a standard USB mouse works. (The existence of the laptop's own pointing device may make this less-deterministic, of course.)
