what is the most likely cause of having all the brakes lockup?
it started with the front brakes getting so hot they were smoking. then the back brakes locked up so it couldn't be moved. after sitting for awhile it can be driven again but the brakes will eventually do it again.
Too much moisture in the brake fluid, flush the entire system, replace all of the rubber brake lines. I had a Honda that would do the same thing, I flushed out the brake system and it lasted about month and started doing it again so I replaced the brakes rubber hoses and flushed it again, no more problem.