Only the "Dell" USB keyboard worked. If there is some other hardware issue then you replace the machine (these are pretty cheap today.)
I see it has front and rear USB connections so I always try the other USB ports and some models have a PS2 keyboard which we always try.
Hey, Friend i have Dell Optiflex gx 280 Desktop System.i m facing problem with keyboard while starting Window 7. When i start system i am unable to enter BIOS or Advance Boot Option. If my System shutdown unexpectedly in that cases i have to wait so much time in startup of computers.