USB devices not recognised when plugged into USB port

Archived from groups: microsoft.public.windowsxp.help_and_support (More info?)

If I plug a USB device into a USB port (eg a memory stick), XP does not
recognise that any hardware has been plugged in. However, XP will do so if I
do a reboot with the device plugged in.
Device Manager specifies that I have, under the heading of Universal Serial
Bus controllers, the following devices installed -

Standard Enhanced PCI to USB Host Controller
2 x Standard OpenHCD USB Host Controller
6 x Unknown Device
3 x USB Root Hub

I have 6 USB ports installed and all will work with a device plugged in only
after rebooting with the device plugged in.