How reproducible:

Always.

Steps to Reproduce:
1. Log in to GNOME 3.
2. Lock screen.
3. Hit right mouse button, as one frequently does if carrying an open laptop. May have to hit it twice if screen is off.
4. Screen goes black.
5. Login prompt appears as if logging in to GDM (not unlock screen).
6. Don't pay close enough attention to notice this isn't the unlock screen.
7. Type password.
8. A new GNOME 3 session starts.
9. Ask where all my windows went.
10. Realize what happened.
11. Curse.
12. Log out.
13. Hit control-alt-f2. Unlock screen appears.
14. Enter password.
15. Realize all the session daemons (gnome-keyring, sometimes network manager or pulse) were replaced and no longer work.

Actual results:

Two login sessions, one that works but has no windows and one that has all my applications open but no longer functions properly.

Expected results:

See unlock screen (or nothing).