Keyboard Inop in WINNT

Why does my users keyboard not respond once WINDOWS NT banner COMES UP? It responds okay prior to the banner or if I boot up with a DOS boot diskette. It is a definite hard drive problem as I have swapped the drive to another good PC and have same problem. Running WINNT repair has not helped. Before I laplink his files to a new drive and reclone his old one,any ideas?