I'm apperantly always facing this problem; when I install a mod that either adds content or rather improves it the game seems to take it out on the ending. Though the time it does is random; it just says "New Vegas has encountered a problem". This and I'm really tired of disabiling mods to get my ending working when overall the game works just fine.

Would there be any specific mod that might do this or is my Vista just screwed up?

Mods have a nasty habit of screwing the game up. If you're going to use mods, you simply have to be prepared to have your game do funny things. Do you use Fallout Mod Manager?
It's likely to be mods causing it, but if you don't know for sure go through the ending with all mods disabled. If it works fine, then I guess you can then go through the ending over and over, disabling a mod one by one til you figure out which one it is.
If you don't want to do that, stop using mods, or stop finishing the game, or just carry on disabling them just before you finish. FOMM makes it all a bit easier, so if you don't have that I suggest getting it.

you should use this in lieu with FOMM



http://www.newvegasnexus.com/downloads/file.php?id=34703

I do use Fallout Mo Manager for i'm fairly familar with the engine they use it on. And i've been into the modding community ever since the "unoffical mod" for Fallout 2.

Problem is; I've done it before. I tried doing it without mods and cancled the source. It seems either A; altering the mass of NPCs is doing it or B; adding new quests is doing it.

edit; Apperantly the FONEdit at least helped it get to the NCR Ranger ending, which is pretty damn close to the end of my ending (total of 8 minutes long). Just gotta figure out whata bugging it out...