DVD problems

I have been using Ulead video Studio 11 plus for about three months. I've found it a very easy software to use but I'm having problems with finished DVDs. I use a Canon HG-10 HDD camcorder to do interviews which I then edit and add JPEGs to the finished product. The DVDs' play great on my computer but sometimes they stop when they are played on a DVD player. The picture quality is good but I'm also seeing sync problems with the audio. I was hoping someone might know if the type of media I'm using could be a factor. I've been using HP DVD-R 4.7Gb discs. Are they a potential problem? I'm also wondering if I'm trying to put too much on each disc. The burning function will compress the data I believe. I'm also creating video files prior to buring and I'm creating those video files using the NTSC DVD 16:9 setting. I hope someone can help me.