fallout 3 keeps locking up

I just got this game the other day via steam and I've finally found an internet connection good enough to download it on. So it finished downloading today so i decided to play it. Im running windows vista via boot camp on a 17 inch macbook pro with 4gb of ram intel 2 duo core 3.06ghz processor and a 96000m nvidia geforce graphics card. Everything was running fine from when i was born to my birthday to the goat test and then all of a sudden, when it was time for me to leave the vault, it would lock up on me. It locked up on me once and i thought that was just a random occurence and that it wouldn't happen again. It didn't for a while but once I came to the part where the overseer was interrogating his daughter it was guarateed to lock up at any time during that period. When i mean lock up i mean the game would behave as if there is no keyboard or mouse. I can't move the mouse, I can't type anything. What I am able to do is alt tab out of the game. When i try to restore the window of the game after i alt tab it, the bar (I forget what its called) that is on the top of every window with the close restore maximize buttons, would come up but that would be it. The task manager says that the program is responding, but I would have the end the task because I can't get any further. I don't have any other problems with games that i have downloaded on steam such as left 4 dead and I don't have any problems with games that I've installed through a cd like republic commando. This is the first and only game that does this. I know there are alot of people with freezing problems but none of them seem to fit my case especially since im running windows on a macbook. Any suggestions?

 

yes i have just completed installing the patch and i get the same thing.