I've encountered a problem, and I've yet to find any listings on the web of others encountering the same issue.
I am not able to begin the final mission at Cronos Station. I respond to Hackett with the "let's go now" option, watch the final nightmare sequence, and talk to EDI, then, as I'm choosing my squadmates and their weapon loadout, the mission failure music begins and I see the game over screen.
Is this a glitch?
Almost sounds like you do not have enough troops to even do the final mission and just fails you. Need to go to your war room on the Normandy and look at your War Assessts and see how many you have and if you are above the minium requirment and what not. Also if you click more information in there you can see your chances of winning.
If you dont have a problem with how many troops you have ready to go into the final battel with you, than I am not sure why it will not let you move on in the game.