Possible causes are viruses, spyware, and hardware malfunctions. On the other hand, there also are cases where a user was too zealous with the automatic cleanup features of their web browser or other programs and deleted some essential system files.
The game can also break the startup when exploting outside of the game. There is now a bug where if you die, you're stuck at the loading screen if you have that option enabled in your console (usually the nv_path="@doom.vmx" or doom3.esm line). It can't be fixed by restarting the game, but if you restart the computer after loading the game, it can work again.
 Fallout 3 (Doom 3) + Bethesda.net version of Fallout 3 + Add-Ons (Doom 3) + Fallout Source 2010 mod. () Fallout 3 w/ add-ons + other + mods. I did NOT modify anything, but i had to install all add-ons manually. (Anyone can try and do the same without problems.) () Fallout 3 vanilla. /// no add ons. (Bugs people found: ) See  for finish of the video. (I'm not -dbg, so i can't run the game with minidump) :  Test #1 (Wsod exception, but no crash.  Test #2 (No exception, but can't finish download & execution of post_game.exe rights now. Error opening folder))  Test #3 (No exception at all.)  Test #4 (Exception, but no extra windows, and no crash.)  Test #5 (No exception. Can't download post_game.exe.)  Test #6 (Exception, but not extra windows (No crash during download & execution of post_game.exe))  Test #7 (Exception, but can't download post_game.exe.)  Test #8 (Exception, but can't download post_game.exe.)  Test #9 (Exception, no extra windows, and no crash.)  Test #10 (Exception, but no extra windows, and closed by myself (No crash during download & execution of post_game.exe))  Test #11 (No exception, but getting error message that i didn't gto remove my mods (No crash during download & execution of post_game.
Undead Labs's own take on the Fallout franchise isn't expected until future Fallout projects, according to their official blog. The Kotaku report was sourced from a statement by studio co-founder Chris Ashton, who apparently stated the following, d2c66b5586