My experience with that scenario is a worn ballscrew.
The wear in the ballscrew causes the control to think the screw has gone to the requested position, then the control looks to the scale for verification and the scale says WRONG so the control starts hunting for the correct scale position.
The quick fix for this is to unplug the scale and run without it.
My uncle has been running his Fadal for a year this way. It is out enough (doesn't take much) that it hunts but not enough to be detrimental to his work considering it is his "roughout" machine.
I dont know if he has ever had cold start issues, but his machine never gets turned off either.
I suppose you could plug your scale back in before you restart from a power-down situation.