A couple of weeks ago I started a thread about how to turn off autoplay compeltely on DVD drives, in order to prevent DVd software from self-installing- & posted isntruction s for doein this which I had then found via Google.

I've just found a horrible side effect of this today- when I began copying DVDs to a new USB drive . All of my DL copies were giving read errors , even though they had previously worked OK. Further testing showed that the failure was always with the VOB file which spanned the layer break. Windos gave a read error with that file, and DVD player software froze when tested on that exact VOB.

Now the only change to my PC that I'd made recently was this disable autoplay thing - (and a side effect of turning autoplay off completely is that Windows no longer really knows what's in the DVD drive e.g. it does not display a title and does not update explorer when you swap out DVDs.)
So I wondered if, because of this, windows was not properly aware that it was working with a +R DL copy.

So I've now reversed the Gpedit & related resistry settings so that autoplay is back to nomal & My DL copies are now usable again!!!

I don't profess to fully understand it, but it's a big relief to find that my DL backups are not corrupt after all ! ( It only affects copies I think, because I've played DL original movies on my PC OK since truning off autoplay & they were not affected )