I haven't got an actual blue screen since that, but things are still pretty messed up at the USB level. The typical thing is that when I come back to the computer after a while, the USB keyboard and mouse are dead. i.e. they're acting as if they're disconnected. Unplugging and replugging them rarely helps. I also saw the same behavior with a USB card reader. I have tried a different keyboard.mouse with same results, so I know it's not the physical devices that are to blame.
So basically, it seems that some USB ports get turned off after a while. Rebooting the machine always fixes it.
Is it possible that it's some kind of hardware issue on the motherboard, or whatever piece controls the USB port? Or maybe still a bad driver?
If needed, I can contact HP to try to get a replacement, but I'd rather find a software fix if at all possible!
Any brilliant ideas?