Copied DVD freezes at beginning only

I own all episodes of “Buffy the Vampire Slayer” and want to make back-up copies on DVD. But when I copy to DVD the new copied DVD would freeze for a second in several places only near the beginning and then would be fine after that.
This also happens with other movies I own and try to copy - and only at the beginning. The movie plays perfect when copied and watched on my hard drive but when burned to DVD has this problem.
I’m using Sony DVD+R, XP Windows and have an HP pavilion a720n computer. The burner Philips DVD8421 can only burn +R. I’m using Decrypter only and not shrinking the movies at all.
I have played the copied DVD in several players and on the computer and has the same problem when played on all of them.
I think I used a few Verbatim DVD’s and had the same problem.
I think it’s some kind of burning problem because the movie plays fine on my hard drive.
But why does this only happen at the beginning ( between one to ten minutes into the movie) and not the whole DVD?
Has anyone come up with a solution or know what causes this?
Thanks for your help.

could be your dvd writing drive re-calibrating to higher burn speeds??

along with you stand alone dvd player is picky??

take the advice below.