Windows 2K, USB hub and an error

Using Win2k and a USB hub to plug in a number of PDA devices that use USB. The hub is found OK, and drivers load correctly, however, the remaining devices plugged into the hub do not load. When you look at device manager, the exclamation mark displays next to an unknown USB device. If you try and reload the drivers, an error is generated: “The instalation failed because a function driver was not specified for this device instance” PLEASE HELP!!