After getting all the way to The Missing Link Chapter 5, there appears to be a bug in The Missing Link that may prevent you from completing the game. The game will freeze and the console must be restarted.
So far Eidos support has no resolution for the bug. Restoring previous saved games and deleting the DLC and reinstalling have not resolved the issue.
The only solution may be to start the game all over.
I've run into this on Chapter 5. Everytime I get to the BioScan chamber (after the alarm sounds and gas decontamination warnings are coming). Am I really going to have to start the DLC all over again?!?! Damn. I've gone this far with no weapons, no Augs, and no Praxis upgrades. Not really looking forward to starting over.
This freeze is consistent for me. I can't get past it at all... :-(