Check the file sizes of your converted files, chatman. The ISO standard for DVDs does not allow any single file to exceed 2 GB in size (that's why the 3.65 GB original was split into two files in the first place). Although a standard DVD can hold up to 4.7 GB of data, no single file on the disk may be greater than 2 GB. Even a long play DVD movie of 4.7 GB is stored on the DVD as a collection of smaller "chapter" files. You don't see that when the movie plays, because the files are usually called sequentially, without any prompt from you.
Your burner program may be refusing to write to the DVD because it can't, if you are trying to burn files > 2 GB. Some burner programs won't warn you of this ahead of time, and will attempt to burn the first 2 GB of data to the disk, then the program will hang or crash.