I have the same problem under knoppix 4.0 but in knoppix 3.6 my USB Motorola Surfborad Cable moden is autodetected in the boot sequense, it seems that there the hotplug autoscan sequence works fine.. i bealive that someone screwed up this at 4.0, hope there is some way to repare this cuz i cant make internet work on this new knoppix version.