Recording Error "Can not record on this disk/E4 ... (by 5 users)

I recored one time on a DVD-RW disc, worked fine.I went to formatt the disc to reuse it,seemed to do fine. When i put it back in to record from ( timer recording )it loades the disc then trys to formatt, after about 3sec.it gives me a message: Can not record on this disc.ERROR-E4/54037380.
Records fine with DVD-R disc.
I have tried new disc,different brand disc,unpluging the unit.My son has same model recorder he has no problem recording.I used the same disc he used (new & used)to do a check on my unit, no luck. Can you help?
When I load a DVD-R disk I get the error message Recording Error "Can not record on this disk" at the bottom of the error box is E$ 54037380. I've turned the machine off and unplug it but still the same message comes up when I load a blank disk. I have recorded over 45 events before this started to happen. Please advise.