I am having the same error on my mazak screen,
did you find a way to clear out this error since you had it in april/2010
I have tried this procedure for T2 M2 controls, but if you have FX701 PCB then it should work the same
1) Turn off machine.
2)On FX701 PCB change you will be able to see an 8 position DIP switch on top of the board without having to remove the board. (the dip sw may have a clear plastic cover, remove it) Change the second sw from top to bottom.
3)Turn machine ON and leave it on for a few minutes (3 or 4 should be fine)
4)Turn machine off and change sw to its original position
Hope it helps
By the way, I have a T4 lathe without any manuals, could you send a copy if you have them? operation and programming?