My mac bookpro screen hangs and freeze after restarting it displays black screen
The 3 beep sounds indicate problem with your EFI.

EFI is located on your disk in a hidden partition and is mainly responsible for booting and other key functions.

It is possible you do have a disk error (even if the "authorized dealer") did not find anything. I would suggest you use the Disk Utility and check your disk again and while at it repair the permissions.

Check your version.

How to repair EFI: Find your EXACT model here.

http://support.apple.com/downloads/#macnotebooks