the first step in troubleshooting a computer:
back up your data, preferably to an external hard drive
reinstall the operating system, upgrade to a more recent one if possible (hardware)
restore your data from the external hard drive
heh, just kidding. it is actually one of the last sets of steps to take.
like the others, uninstall the device, through the device manager.
however, unlike the others' advice, physically remove the device in question.
then restart the computer without the device, letting it fully boot.
back up the registry, run the registry cleaner, make a second backup of the registry.
turn off the computer.
physically reinstall the device, connecting any necessary cables.
turn on the computer, letting it fully boot.
if windows does not install the necessary drivers, use the provided disk, or download new drivers.
if the above does not work, post again. more information, such as the operating system, make and model number of the computer, et cetera.