Hi, i played around 40 hours now and all of a sudden after i completed the Bodyguard quest at the Silver Rush my game always crashes when i assign a hotkey to a weapon in Pip Boy..
Now i cant assign Hotkeys anymore and if i do my game instantly crashes -.-
Does anyone know about this problem?

It happened to me as well, but only much later in the game when I'm about to attack Caesar's Legion for the final battle.

I'd say something is screwy but that would be an understatement when NV is involved isn't it...

There's a work around for this:

http://www.gamesas.com/index.php?/topic/1136139-ctd-on-hotkey-assign-fix/

Wow! Thank you for that, it worked for me