It's a copyright problem; However you still should be able to play on a Computer. It's normally a problem with the Blu-ray software, you need the latest updates to your blu-ray program. Not sure what you are using - I have cyberlink's on two desktops and total theatre on 2 laptops. (all four have blue-ray drives, desktops are recorders while laptops are Blu-ray rom/DVD-rw drives.
A second option is to install Anydvd. I bought that and have it install on my older desktop (E6400). It removes the copy protection before it gets to the player software. The are very good with updates for this problem. It's about 75 quid w/2yr subscrition. I got mine with lifetime subscrition (the were getting ready to go the route of annual fee).