(and I personally I would not use Nero to encode to dvd, you should first encode to dvd mpeg, then author the mpeg, and then only burn with Nero - the problem might BE that you tried to do all of that with Nero, which is not designed to be an encoding program, it is designed to be a burning program with encoding as an after-though - I didn't even know Nero CAN encode to dvd format from another format)
...do you have a slow computer?
...were you multi-tasking? (running other programs)
A person who asks a question is a fool for five minutes, a person who doesn't is a fool forever...