Unfortunately, I have the same problem as well, and it's killing me. I have a HP DV5020us laptop, and this problem happened to me about 3 days ago.
I set Napster to download a bunch of songs, and then went to class. I got back a few hours later and my computer had frozen up. I had to push the power button, and upon rebooting, none of my USB devices were recognized.
I'm at the end of my rope, here. I tried regedit fixes, turning off power and letting the capacitors bleed off, USB stacking, you name it, I tried it. I'm really frustrated, as I need to use my USB devices.
It's interesting to see how this has a. affected quite a few people recently, and b. affected a couple other people with HP pavilion laptops...