File reallocation error

Can someone shed some light on this problem?

I have alot of movies that are in avi or mpeg format. I use Winavi 6 to convert these movies to dvd format. When it converts, I get no errors reported, and it converts successfully.
My problem come in when I want to burn the converted movie on Nero. I add the dvd files as usual and click burn. Nero gives a “file reallocation error”. and “File size is not a multiple of a logical block size (2 KB)”. I can choose to ignore it, but then the movie does not play properly on my dvd player. If I do a copy of dvd, I don’t have any problems when playing it on my player.

Can someone please help or explain why this is happening.