Leviathan issues
I have had so many issues with this game its sad, I have restarted and worked my way around most of them. BUT I started the Namakli dig site mission ( had to reinstall after constant crashes at the first into part to this mission) , now after I get the bridge fixed, I cannot go down the ladder to get on with the mission. I have tryed exiting the game, and restarting the mission (even with new team mates to see if that was the issue) but nothing. Shepard just sits on top of the ladder acting like he is going down for a few seconds then stands back up. I have been through a few different PC beta's, and NONE of them were as bug filled/choppy as this game I just bought (with all of the extra content)!
This is the most reported ME3 bug on this forum. I'm surprised you haven't found the workarounds that have been posted here before.
There are several possible workarounds, but none of them are guaranteed to work. One is mentioned above. The other two are playing in windowed mode or constantly lookign up while approaching and descending the ladder.