First up, your English is great. I am glad you can understand me. My only other language is German.
I did not get to the computer last night as my family needed me all last night. However, my friend did bring round the DVP 520. I tried the previous DVD+R DL and it did not work, as I already expected.
However, I have downloaded DVDinfopro and will use it to change the booktype to DVD-ROM. After that, I will burn a another DVD+R DL and hope that it one of the 99.99% of discs that works OK !!
Thanks for your help. I will let you know how I get on.
By the way, I have a Sony DRU 710A for a drive, using DVD Shrink 3.2 and Nero 6 SE.
The media is Trackdata, I think.