I am not familiar with Videopad, but know the processes and operations involved with video edit and then DVD.
You are starting with a Video + audio stream in an AVI or MPEG or other format. When you edit, you are cutting and pasting sections. If you do not fill the audio to the video, you can get gaps. You need to review the original video file for those audio gaps.
If the original Video/audio is clean, the steps then convert it to DVD compatible in a 2 step process done by the software to get it to .VOB files. Depending on the audio files you used, some may not convert properly. The .VOB 's become an ISO for burning.
.VOB's to ISO usually go OK, and ISO to DVD go OK as long as no scratches on the disc, and that causes audio+video freezes; not just one or the other.
It could also be lost if you have multiple audio tracks, and a second track is not picked up.
Where the audio cuts on the DVD look at the audio/video file in that section and see what it shows.