#1 Rule : never update ANYTHING until you have verified "no problems"
by checking numerous reports online
did it work on the new PC before you updated the phone
i have brand new Win 8.1 HP laptop, and i've No trouble with my Android phone
plug the phone
don't try to do anything with it
then go to control panel
then device manager
go down the list find your phone AKA media device, might be in the USB list
might be under the disc drive list
click on device
and choose update driver
you might have to do a delete driver first
then repeat the update procedure
