I usually blame it on the gremlins first.
One thing i would check for is grounding issues with your case, make sure that your front panel isnt shorting anything, also inspect the board near where the USB header is, make sure nothing looks cooked near there.
That's what I suspected too, but could find no evidence. Both USB ports work. It could be an intermittent short that occurred when I tried to plug into the port. I was planning to upgrade anyway, so it looks like a new MOBO and CPU is in my immediate future. I was holding out until Sandy Bridge MOBOs back on market, but that may be another month or two.