Does the display say that zone 4 is on when you test it manually or does it say zone 1?
If it says zone 4 try this. When zone 1 is running when it's not supposed to, disconnect the number 1 wire from the controller. Did the valve shut off?
If it shut off the controller's putting out a signal when it's not supposed to. If zone 1 is still running after you disconnected the wire then you have crossed wires in the field.
There might be bare wires intermittently touching each other somewhere causing various valves to run when they're not supposed to.
I have another question, does valve 4 and valve 1 run at the same time? If it's crossed wires I'd say they would.
--
You could try resetting the controller.