I just loaded the game now after a little break because of all the bugs. Suddenly I found that Cass had been (finally) respawned outside the gates to the Strip, after having fallen into the void inside the Lucky 38 (I wrote a separate thread about it - "Malavok's Verdict"). But now I can't even get back into The Strip because the door has been reset or something, it requires a key. o.O

WTF is going on? anyone else got this critical bug? I mean, The Strip is pretty important for the main questline lol

Many NPCs have been given keys to the strip gate as a way around this glitch. It should be addressed in the next patch or so but for now you can do a couple things to get around it:

-killing one of the gatekeapers while sneaking and from a long distance (sneak kill from long distance will not damage faction standings)
-bring up the command console, click on the gate (it should say door or gate in white letters up at the top of the screen. if not then move closer) and then type "unlock"
-use the console command "player.additem 00119875" to add the gatekey to your inventory.

The last solution is probably the best if you have met the requirements to get in but are simply locked out for no reason. To avoid it interfering with steam acheivements you should save the game after adding the key and exit and restart the game and then load the save. Steam acheivements are disabled for the session in which you use the console but not for an entire playthrough.

Could just use the train too. This bug seems to occur when you and your companions are on opposite sides of the gate. Take the train and then when you go thru the gate again make sure your companions are with you. Shouldn't be locked anymore.

Yeah - only caveat with the monorail is it requires you have at least accepted status with NCR. If you aren't their favorite person in the world right now they may open fire on you.

Ok thanks guys, I'll go and try out a few things. Just glad I finally got my Cass back, now on to unlock the gates lol.