You beat me to it Simon, I was just going to post this....
I just found an old DVD +R that I burned a couple of years ago, and it plays fine in my DVD ROM. And now I can't find the DVD that Michael burned for me, and while I was at, I stepped on a small mirror and broke it..... so that's how many years bad luck..
I thought it had something to do with being finalised, well I said finished. So how do you finalise them and can it still be done on the DVD Michael burned for me. (If I can find it.)