Trouble making backup copies of DVDs from my recorder

I have an LGR435 DVD recorder, with which I have been converting my camcorder moview to DVD.

Recently, I have been trying to make extra copies on my computer’s DVD burner to share with friends.

However, it almost always fails when trying to duplicate these DVDs. I have tried both Sonic and Nero, with an LG-4163 and BenQ DW822A. The only DVD’s I have succeeded in making copies of are ones where all the .VOB files are under 1gb.

Any DVD with files over 1gb fails to copy. I would appreciate any suggestions on how to overcome this problem.