So, I recently did a fresh install of Ubuntu GNOME 13.10, added the gnome3-team/gnome3-next and gnome3-team/gnome3-staging PPA's, and upgraded to Gnome 3.10. (Also using a dual-monitor system, 1920 x 1080, Nvidia-319 driver.)

Everything was running fine after the updates (including Nautilus, or "Files"), but when I opened Nautilus, at some point, the header bar was gone, and it got stuck in full-screen mode. The header is there for every other application, though. I can't resize Nautilus, I can't move it with the Alt+F7 hotkey. I can, however, make the sidebar disappear with F9 and make the program close with Alt+F4. I can also bring up the window menu with Alt+space, but the options to "resize" and "move" are greyed out, and the "Move Titlebar Onscreen" does nothing when clicked. Attempted solutions:

1. I uninstalled, ran apt-get autoremove clean autoclean, and re-installed Nautilus, including any subsequent applications that were removed -- no fix.

2. I installed and tried replacing the titlebar theme with Ambiance via Gnome Tweak Tool to at least restore the header/title bar -- no fix.

3. I created a new user, logged into that, and opened Nautilus. It DID open up in the windowed mode with the header bar, but then, without my involvement, went to full-screen without the header bar. Same problem.

Running "sudo nautilus" from the terminal does open it (full-screen, without header), but gives this error:

(nautilus:7531): Gtk-WARNING **: Failed to register client: 
GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files

Here's a screenshot of the complete Nautilus dialog box: