That sucks.... I don't know much about DVD burners, or why it would have you lower your resolution.. HOWEVER
1) Update your graphics cards drivers - if you have the latest versions, reinstall
2) Update your DVD playback software - if you are using powerdvd, download the latest patch, if you are using Windows Media Player, go to windowsupdate - you get the point.
3) Make sure no program running in the background is eating your RAM, or CPU cycles. CTRL ALT DEL before you open your DVD software, and close every program running - see what happens. Also, check out your CPU usage.. if its REALLY high (I would say above 50 is bad, but 90 or up is really bad) then you know something is not right.
4) Reboot your pc and only load your dvd software, don't run anything else - maybe that will help.
Its been my experience that DVD playback on pc's is usually much trickier than one might think. One night I tried to watch Seven, and my roommate and I downloaded about 15 different DVD playback programs (shareware included) and compromised by having to shutdown every 20 minutes and restart because the sound and video didn't synch after that point...