With any PC game and the numerous computers out there with thousands if not millions of possible hardware combinations there are bound to be problems. To help developers out it maybe best to create a compiled/consolidated issue thread to recognize problems. I'll try to go through and record all the known problems and possible fixes involved.

1. Graphics Settings Not Saving (Possible Fix)

Problem: There was an issue where graphics settings were not being saved for some reason. Whenever people would click play from the steam games library then options it would open up the prompts. Clicking OK would not save the settings and they would revert to whatever they originally were.
Developer Fix: Not In
http://www.gamesas.com/index.php?/topic/1122866-graphic-settings-not-saving-fixed/page__p__16513266&#entry16513266: First mentioned by Shadow12 players should go to File and select the "Play in Offline" mode/setting. This will cause steam to restart itself in offline mode, but allow players to play their games. Players should then go to Fallout New Vegas and hit play going to the options menu. After setting your options you can then hit OK with them permanently saving. Once this is done you can set yourself into Online Mode again or play in offline mode if you like.

(Note: I can confirm this fix myself I had the same issue and was able to set my resolution to 1920x1080 from 1280x720 doing this method as well as setting my AA from 4 to 8.)

2. Saved Game Issue (Possible Fix)

Problem: Saved game files are either not showing up, not working, or causing people to crash.
Developer Fix: Not In
Player Fix (Possible): There are several player thought of fixes for the not showing up or not working problem. http://www.gamesas.com/index.php?/topic/1123323-solution-to-fixing-steam-startup-crash-quicksave-problem/ to the current thread about this to help out some users. It has also been recommended to try to run the game in offline mode to fix the problem.

3. Steam Community/Cloud Issue

Problems: Game may crash after hitting play as well as causing other problems.
Developer Fix: Not In
Player Fix (Possible): Uncheck the Enable steam Community In Game. http://www.gamesas.com/index.php?/topic/1123087-fixed-my-problem-crashing-after-pressing-play/

4. Crash While Entering or Leaving the VATS

Problem: Using the VATS ability causes the game to crash.
Developer Fix: Not In
Player Fix(Unknown): no known player fix exists at this time that can be confirmed legitimately

5. Weapon Modification Issue

Problem: Modifying a weapon causes the item to be replaced with an ! icon (Possibly isolated to the 10mm pistol) http://www.gamesas.com/index.php?/topic/1123445-weapons-model-replaced-by-large-icon/
Developer Fix: Not In
Player Fix(Unknown): No known player fix exists at this time that can be confirmed legitimately

6. Non Player Character Slowdown

Problem: NPCs slow down due to some reason in game
Developer Fix: Not In
Player Fix (possible):http://www.gamesas.com/index.php?/topic/1123107-fps-drop-when-near-npcs/ by the moderator Ratwar with possible solution



If there are any bugs that I missed please feel free to post them and i'll update this section. Hopefully keeping the issues in 1 thread can allow developers to see what issues are at hand and work on the most problematic ones.