you gotta jump through hoops to get vlc to play blu-rays and then it doesnt yet support menus in blu-ray....i agree with Kyllien upgrade to powerdvd 12..avatar has some funky copy protection on it.....It's not a codec problem..........
For the retail Blu-ray disc, there are several tools available, PowerDVD(time-limited free trial), Macgo Windows Blu-ray Player(watermarked free trial), Arcsoft Total Media Theatre(time-limited free trial), WinDVD(time-limited free trial). Hope this can help you.
Last time i used a WinDVD trial(only a year ago) it did NOT have bluray playback so I moved on to power DVD. it worked perfect so I bought it.
http://regionfreemovies.com/ search for avatar and click on the closest version description based on your nationality and click region detail icon.
Some are region free and some are locked depending where you live. Try your luck with setting Bluray drive's Region to A B or C according to the movie.
I would not do this, The drive MAY have a limited number of times you can change the region code(or at least if i remember right).
Third party software can emulate a code, but changing it on the drive and you may regret it when you run out of changes.