I have Steam, that's not the issue. The issue is that I have a hard copy of the CD that I am installing with and yet Steam insists on using my painfully slow internet connection to download the damn game.
This happened to me, but I do not have that slow of internet. I waited for it to finish downloading, and now it crashes for me every time. I get this error "Fallout: New Vegas has stopped working" after I run F:NV from steam, it then a window pops up, and I click run F:NV. I always have steam running so it just took over the install. I put in my cd-key, and now it just doesn't work.
I have tried what others suggested, and I have just installed from downloading and it keeps crashing. Yes I updated my drivers too.