rudey D

I've got a Trace Elliot GP12-SMX combo 15 as well as two additional 15" speaker cabs and a Trace 4-10" speaker cabinet. The knobs cackle on the GP 12 head but the previous owner gave 5 new pods with the amp. I have two questions : #1 Are all Trace Elliot cabinets 8 ohm? and #2. Is there something in the amp that shuts it off to keep it from over heating or blowing a fuse?? It recently shut off in the middle of a song. I turned it off checked the fuse and chords etc- next day turned it on and seems fine since. The only difference is I had the 4-10 cabinet hooked up to it when it shut off. I haven't plugged in a cabinet since because I thought I would ask someone first. Any thoughts / help would be greatly appreciated. Rudey D I am obviously a new member.....