What firmware version do you have?
If you do not have 2.12 try downloading the .iso to a computer and burning it to a CD.
Then turn on the blu ray player and insert the CD you just burned.
The update took quite a while before it gave me the messaging asking if I wanted to update the firmware so don't be tempted to turn the player off and back on.
See if this fixes your problem.
I got the BD-P4600 for Christmas last year and have loved it for 9 months up until I recently upgraded the firmware, now it will no longer play Blu Rays. It just ejects them after a few seconds and says "This disk cannot be plsyed". Tried 6 or 7 disks which all played fine before the firmware "upgrade". DVD's still play fine and so does Netflix. Called technical support and got no help other than I have to send it in at my own cost and pay for labor to fix something that their firmware upgrade broke. Was transferred to their "Executive" Customer Relations Dept. which was absolutely no help either, telling me sorry but you have to pay the labor charge to fix something our firmware update broke. Also told there is no way to reset the firmware back to it's original state without sending it in for service. I own two large screen Samsung TV's, a Home Theatre, Computer monitor and bought a Samsung TV for my parents but this will be the last product I buy from them. As they say, you find out what a company is worth when you need service from them and Samsung has failed me when I needed it. Transaction # 4007289067