FAULTY REMOTE,maybe not,sometimes if you change channels backwards and forwards too quickly the remote may lock up and not do anything,this is a fairly common occurence and can happen to almost anything,satellite tuners seem to be a favorite,the first amstrad tuners had this as a common fault but the cure is just the same,unplug the unit you are trying to control from its mains socket and leave for 5mins,plug it in again and switch on ,99 times out of a 100 it will work again.