just recentley the game has started crashing every time i enter combat it hasnt done this before, altho it has crashed randomly before but now its every time i enter combat so if there is a fix i would like too know if not maybe this is something bethesda can look into

I am having the exact same issue, it started maybe 2-3 days ago. I had been playing for a few hours then all of a sudden it crash, and started crashing every single time I started killing anything. I restarted, reinstalled video card drivers and just about everything else, its starting to look like a fallout problem and not a computer problem.

Are you using mods? What happens if you start a new game?

You can try reverting to a backup save (either quicksave or autosave will do)
Look in C:\Users\\Documents\My Games\FalloutNV\Saves
Simply rename quicksave.fos.bak by deleting the .bak portion. You'll have to move the original.
Works the same way with autosave.fos.bak

i tried what you said and it did not work and i do not use mods i did cheat which i think is what may have caused this. i loaded a save before i did the cheat and i can go into combat withh out crashing so i assume Chezza may have done the same

What cheat did you use? If you can load a previous save or start a new game without crashes in combat then its probably the saved game.

i used the special points cheat and tagskills cheat but it all started when i reached the cove where you take the boat over too ceaser area any saves in that area are crap wich is 2 or 3 saves