Phillips Mdl 72/99 DVR

My recorder writes fine to DVD+RW disks but when I try to record on a DVD+R, I get an immediate disk error and the unit pretty well goes nuts. I have tryed several different media brands and speeds with the same results. I tryed Phillips tech support but they were just interested in collecting $15. I just need to know if this is a common problem or does the unit need repair. The unit also will play other disks DVD+Rs that have been recorded on other machines.
Any suggestions would be appreciated.