i may have misunderstood but if it works with the sg and not the explorer im guessing your explorer has a problem. Just try replacing the batteries and cleaning the inputs, outputs and effect loop jacks (if it has one) and see what happens.
when it shuts off is there any sound what-so-ever? if it 'dies' again try strumming hard and seeing if any sound comes through. What do you mean by freak out? crackling or sound fading/kicking in and out?
Thats about all i can help for, hopefully someone more experienced can help