Windows 7 says cannot play DVD

I apologize if this topic has been covered. I tried to search.

Any way, here is my problem. I built a new desktop computer, intel i7 cpu, and ATI HD 4850 video card. I took an old Benq 1620 DVD writer from my old xp machine and installed it on this windows 7 machine. This BQ 1620 has B7W9rpc1 on it, i.e., all regions.
The video card is connected to a 1080p tv vis HDMI. When I play a legit region 1 DVD on this new windows 7 machine, it says something to the effect of wrong region. But I can play previous backed up dvd’s. Only the originals cannot play.
Infotool says it has B7W9 firmware , Region control is rpc1 and region is all.

Is HDMI bad news here?

Please help. TIA.

These guys are good. Take a look at the link below, they just might be able to help you.
Good Luck.

Thanks for the link. It confirms my suspicion that there is no codex in Windows 7 RC, yet. I did try to load some, but did not work. Anyway I tried VLC, as suggested and it works. I think I’ll give up Windows 7 RC soon, since my wireless adaptor card does not work either.