Hello everyone, I am having some problem with Portal 2 game. I have recently purchased the new PC game, Portal 2, I have installed the game successfully, but it is not working properly. It keep on showing black screen, I have check all the things but it not working. I have also checked for the graphic card, my graphic card is ATI Radeon 2400. Even my RAM is 4 GB and 1 GB is shared with Graphic card, I am running this game on Windows 7 ultimate 32-bit, so friends I donít think so that there is any problem with Configuration, so can anyone help me over here? I am waiting for your reply. Thanks a lot in advance.