Since DVD read/write works fine I think it is more a DRM gotch-ya than a Writer problem.
Your GPU is HDMI certified, But is your monitor. Are you using a DVI -> HDMI cable between computer-monitor. Did you run that app to verify system compliance.
My LG-GGC-H2OL worked fine under Vista32 AFTER I REPLACE my excellent monitor. But still had a problem with XP Pro (alas still 32 bit).
Took lazy man's approach, installed AnyDVD. I think they have a trial version that you can try. That should indicate if it is a hardware/software problem (ie DRM garbage).