I have a Dimension 2400 (XP Home SP1a, BIOS A03), and the USB ports are not working properly.  I have a USB2.0 mass storage drive, and it works well as a plug-and-play.  However, recently I purchased a USB1.1 mass storage drive, USB1.1 mouse, and a USB 1.1 self-powered USB hub, and neither of them worked with the 2400 even though they all work fine on a different XP Pro, a XP Home, a 2K Pro.  WinXP kept asking me for drivers even though XP SP1 should has built-in support for USB mass storages, mouse, and hubs.  I have tried to uninstall all the USB devices and rebooted as suggested by someone else, and XP does not install the USB devices automatically.  I have to point XP to c:\i386 to install the USB device drivers.  Even after reinstalling, the USB hub/mass storage/mouse still do not work as a plug-and-play.  Any ideas?

Thanks, NC