From this thread:
http://answers.ea.com/t5/Mass-Effect-3/Mass-Effect-3-Leviathan/m-p/70966/highlight/true#M568
sundance31us 's Response sums it up really well.
Ahh, this glitch I know well...the infamous Leviathan latter glitch. The thread below has a few workarounds.
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Leviathan (any any other) ladder bug! [Edit] Now with Fixes
Thanks to community support, we have managed to come up with a small list of easy fixes that will get you past any ladder that you may get stuck on during the Leviathan mission, or any other part of the game.
Solutions:
- Aim straight up and walk towards the ladder. This may take a couple attempts, but this should work. If not...
- Try walking down the ladder backwards. If that still doesn't work and you play PC...
- Go into the menu and reset the resolution to the lowest possible setting. Then switch to windowed mode. This should allow you to go down with no problems.
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For the first one your Shepard will automatically look down as the animation begins; keep moving your mouse/controller as if you want Shepard to look up.
For the last one if you want to reset your video setting I recommend hitting ESC/pause the minute the ladder animation ends.
