Sorry for the late response.
You could try to check if there is some other application that causes this error. The work to find it can be tedious, but it may help.
First of all I suggest you to remove your computer from any internet connection. This is because if you happen to accidentally shut down something related to your virus scan or firewall, nothing is able to enter your computer.
After that, start closing programs from the Task Manager one at a time. Between each program, try to run Fallout. If the problem exists, close another program. Keep in mind which program you have closed last as if the game starts running properly, you have found the cause of the problem.
After you have done this reboot your computer to reeactive all the programs again. Now, only end the task you ended last before the game begin running properly. Start the game and see if it works. If it does, the problem is solved. If doesn't, then you have to repeat the searching. To do this reboot your computer, end the task that you have already found out, then start endind tasks again in order, starting the game between each task. Do this untill you have found out the second cause.
Do the last part untill you have found all the tasks which need to be ended before the game launches correctly. Just remember to reboot the computer each time you have found new task that may cause the problem. Also be sure that your computer is not connected to internet while doing this just to secure your computer. After you have found the task or tasks, if you aren't 100% sure none of them have anything to do with the security of your computer, you must disconnect your computer from web before ending those tasks and running the game, and rebooting the computer after quiting playing and reconnecting again.
This may help you if the problem lies in the tasks your computer is running. I have solved couple of such problems with this solution.