Welcome to the forums towienet. We don't allow email addresses to be posted in the open forum, so I've removed yours.
As far as your dvd is concerned, I'd just be guessing. Perhaps it is a multi-session dvd that ImgBurn does not support.
Multi-session is when you burn data to a disc, don't close the disc or "finalize" it in a recorder, then come back later and add more.