I was under the impression that USB 2.0 was backwards compatible with other USB standards.
Yes, insofar as a USB 2 port should accept all 1.1 devices, and USB 2 devices are supposed to work in a USB 1.1 port, but this does not always happen.
Where I have seen this is where a USB1.1 port fails to provide sufficient power to a USB2 device (hard disk) - not a problem if you can add additional power via an external supply, or draw power from 2 USB sockets or even a PS/2 keyboard / mouse port.
SD