My Pioneer 107 started off burning + media and was doing well till I changed the media brand, then it steadfastly refused to burn to any type of media after that. I got an error at the end of the burn during the lead-out and it said the burn had failed! I have just built a new system and have now put the Pioneer in to it instead of my old system, and lo and behold it now burns again!!! Hooray I here you say! Well not quite!, it now only burns to - media and refuses to burn to + media. When I burn to + media I get the same problem as before, also during the burn the buffer bar scoots about all over the place from 10% up to 90%. Any ideas what the problem is? Or am I missing the obvious somewhere!