[QUOTE=purge] Disabling an instance would cause it to become invisible and not be effected by any events until it is enabled again.[/QUOTE]
It can be made using simple events.
Make a Boolean instance variable called ON_OFF inside the instance you want disable.
Make all the events for this instance check if the variable is ON, set it visible, so, when it's not ON, it'll not reproduce any of the events nested in it.
Also, make a new event checking if the instance if OFF, when OFF, set it invisible.
It will affect each instance individually, and only the instances with the variable ON will be affected by the events.
For more info about how instance variables works, please, read this single tutorial: Understanding UID, IID, Health of Enemies and Rocket smoke trail.