NEC 6750A CSS DVD playback problem

I’m having exactly the same problem as the following thread
http://club.cdfreaks.com/showthread.php?t=140890&highlight=css+problem

except that I have a 6750 drive and I’m using region 1. I tried flashing the firmware to Liggy’s current 2.61 version but still have the same problem.

Right now I can’t playback any DVDs with CSS. DVDs with no CSS playback fine. I don’t want to use AnyDVD (it does fix the problem). Anybody have an updated firmware that can fix this problem?

Thanks in advance for you help.