Thanks to both of you!!! Cynthia, I have downloaded VobBlanker and have copied your instructions, thank you for the links!
Lightning UK!, yes I'm using convertxtodvd and never thought about changing the output mode to dvd5, it never crossed my mind,(my ignorance!). I am going to try that first, its a simplier fix and the avi files I'm trying to burn are not that great of quality to justify a dl disk.
Again, thank you both for the great replies and I'll post the results.
wiggy