Comment 3 for bug 405237

Can you post a screenshot of the warning? This is likely the gnome-settings-daemon low disk space warning. The new version of gnome-settings-daemon (2.27.4-0ubuntu1) contains a rewritten warning, which should ignore anything which isn't statically mounted via /etc/fstab. If you're seeing the warning from the installer, then it's likely using an older version of gnome-settings-daemon