Comment 189 for bug 973096

I've noticed that this bug is only present when there's high network activity.

If I'm not running any torrents or streaming anything the system will stay logged into the same session indefinitely, but if I'm downloading lots of torrents the session will log out randomly even if I'm not doing anything graphics-intensive (eg, 5 mins ago it logged me out while the only things open were qbittorrent and a nautilus window).

I don't think it actually is a graphics driver issue at all. I'd suggest looking into the network drivers if you're unable to find anything wrong with the graphics drivers.