Comment 27 for bug 1236749

I have this problem too, but not at every startup. It only happens sometimes. Also gnome-tweak-tool often crashes (similar to comment #15 ) and sometimes screen locking behaves weird (see attachment) - I can take a screenshot and it lands in my Images folder, but I can't alt-tab, or anything like this. I have to ctrl+alt+F6, login and run

DISPLAY=:0 gnome-shell --replace

, but sometimes even this doesn't work. Some data:

Ubuntu 13.10

$ gnome-shell --version
GNOME Shell 3.8.4

$ gsettings get org.gnome.shell enabled-extensions
['<email address hidden>', '<email address hidden>', 'Applications_Overview_Tooltip@Tornado', '<email address hidden>', '<email address hidden>', '<email address hidden>', '<email address hidden>', 'nvidiatemp@baco', '<email address hidden>', '<email address hidden>', '<email address hidden>', 'Windows_Overview_Tooltips@Tornado', '<email address hidden>', '<email address hidden>', '<email address hidden>', '<email address hidden>', '<email address hidden>']

BTW Windows Overview Tooltips isn't shown on https://extensions.gnome.org/local/ . I'll disable it and try other workarounds mentioned here.