I'm wondering what is causing VCDEasy, or CDRDAO, to burn disc's that are pixelated in places?

The mpeg is fine and plays perfectly on my computer without any pixelation. But when I burn it it's getting pixelated segments every few minutes. I defragged just before, and the buffer level was fine throughout the burn. I've also burned quite a few VCD's before w/o any problems. Anyone have any ideas what might be causing this?

W98SE, PIII 1gig, Intel 820 MB, 256mb PC800 RDRAM, 40 + 20gig 7200rpm Maxtor's, ATI AIW Radeon 32mb DDR, Soundblaster Live+ MP3, Yamaha 16x10x40x CD-RW.