Picked up from a LinuxToday talkback:

X locking the keyboard ? Three better methods than the reset key : 
  1. the magic key kernel option. 
  2. remotely correct the problem via ssh or telnet. 
  3. the simplest way is to pull the keyboard cord from the case
     and put it in again, the keyboard works. 
     This is by the way a hardware problem I've had on one computer.
     Buy better hardware is the best advice I can offer to you.

That removing/reinstalling the keyboard plug is new to me.