First, try un-installing the driver in device manager by highlighting the drive, rite clicking and select un-install as stated earlier. When you reboot, the driver will be replaced automatically.
If the exclamation is still there, see this registry edit to correct the the problem.
Code 39.
Be certain to
BACKUP the registry. Regedit is not difficult, don't be afraid of it, but never edit it without backing up first
ALWAYS BACKUP YOUR REGISTRY