Hi,
I had same error on my first 5 attempts burning with PD7.
I really don't know much at all about the technical stuff but was originally burning with DVD-R so thought may as well try DVD+R and it worked!!
Now 12 from 12 so far with the DVD+R.
I know you say you were using DVD+R already. So why not just try the other anyway. That bizarre logic worked for me.
Hope it works for you. Cheers
.