The game runs smoothly, more or less. However, when it gets stuck sometimes, or when the infinite loading screen occurs, I can't do anything but to force shutdown the entire PC. When I try to Alt + tab, a windowed blackscreen with a smaller windowed blackscreen at the top left hand corner appears, blocking out everything but the taskbar. Windows key + d and alt + f4 does nothing, ctl + alt + del to get to the task manager opens the task manager BEHIND the black screen. Switching programs also opens the window behind the blackscreen, basically the blackscreen forever stays on top, and there's no way to get rid of it except for a force shutdown. Please help! I'm using windows 8.1, and I don't want to have to force shutdown the PC everytime and possibly corrupt some system files!

Just to further clarify, the game will shut down normally and peacefully if I select the "exit game" option from the menu. However, when the infinite loading screen appears, or the game is stuck, I try to exit to desktop and this problem occurs, and no matter what, the blackscreen stays on top, and my mouse cursor sometimes disappear completely (rather than go behind the blackscreen window).

Get the NVAC mod, that seems to help with crashes, assuming your other mods are properly installed and configured to work together and your save file is not corrupted. Also, if your getting this on cell loads, turn off the Autosave features.

http://www.nexusmods.com/newvegas/mods/53635/?

Does it get rid of the entire problem, or just the infinite loading screen? It only jammed once very recently, right after when I killed the Omertas bosses and told Yes-man about it. But the blackscreen always occurs on any attempt to shut down or minimize the game without using the "exit game" option

If it does not, then you have a mod issue preventing the game from exiting.

Thanks for the suggestion, I'll try it as soon as I can get back on my PC. But this problem has been occurring before I've added any mods, and so far I've only added more grass and more accurate aiming (shots land where I aim 100% of the time)