Has anyone had problems with these disc recorders? I have a secondhand one that seems very temperamental. The carrier keeps opening and closing with a 'check' error coming up. Sometimes it burns a a disc ok, and sometimes it won't even read a commercial disc. If I switch it off it still has a problem, until the next day when it works again. A pal of mine has 3 of these units and he says that they don't seem to last long before faults start appearing. Anyone else had problems?