So, I went to the new Vegas gate, and it said that I needed a key to enter. I've already been in there, passed the 2000 cap check, done missions for House, yada yada yada. My reputation with the Strip is neutral, and I am wearing neutral armor. WTF? Basically, when I get to the gate and says "Open gate to the Strip" it also says "Key Required". Of course, I can't get in, meaning I can't finish a few missions or access my belongings in the Lucky 38. Any ideas how to fix this?

It's a known bug. If you don't want to wait for a fix you go to Camp McCarren and take the monorail in to the Strip. If you leave through the main entrance it should fix the problem so you can use that entrance again.

This and other workarounds here:

http://www.gamesas.com/index.php?/topic/1139743-the-what-i-did-to-avoid-this-bug-thread/page__pid__16674670__st__0&#entry16674670

I had this problem. I was playing a sniper character, and killed one of the securitrons while hidden, from a good distance away. He was carrying a gate key which opened the gate.

Yeah.. just make sure never to fast travel out of the strip.. as long as you leave through the front door it'll stay unlocked until you re-enter the strip. Mine happens whenever I leave Gamorrah.. don't know why. It'll say Key Required as leaving but it allows you to leave. Coming in on the monorail from Camp Mcarren will allow you to leave through the front gate as suggested previously and also negate the key required on entry glitch. All I can think is that it must be lines of code for some specific event that they decided not to use.. but it's getting triggered by something anyway. As long as you do a lot of saving these glitches really aren't such a big deal.. Just save.. a lot.. use different save slots.