seized brakes

Hey guys, the last couple of times that I jumped in the mk1 to give it a run the front brakes have been stuck on. They are mk2 2.0L with a pedal box, they are that stuck on, it chirps the rears on the concrete under the carport if i give it a bit of stick, they let go after a few good hard pumps of the pedal. Its not being used at the moment all it gets is started up and a short run round the block every couple of weeks. So what things can cause this to happen? Id say lack of use is one of them, it will be going in for a blue slip soon but if there is a bigger issue id better get it sorted first.