Sounds like you're having problems with the encoding part of your dvds. If you're capturing and converting from vhs to dvd, it could be the programs you're using causing the dvd to skip. I don't think the Plextor 708A drive is the problem. Check this site for help: www.dvdrhelp.com
They have guides and you may post problems that you're having. It's a great site for information. I do vhs to dvd conversion using the CANOPUS ADVC-100 DIGITAL CONVERTER. I use SCENALYZER software to capture to my PC then use TMPGE to convert to MPEG 2. Then I use TMPEG DVD AUTHOR, NERO to burn the dvd.
If I'm not mistaken there was a post somewhere that said having Pinnacle and Nero installed could have problems with the Plextor 708A drive. Sorry I can't remember where that post was. Check out the dvdrhelp site.