I have CentOS 7 installed with gnome. After some uptime, no items under the 'Applications' menu respond.* I can open the menus and submenus and hover over items with the mouse pointer. They will highlight correctly, but they do not respond to clicks.
The items also do not respond to keyboard navigation where I can still use the arrow keys to move around the menus and highlight items, but hitting
enter etc. does not launch the application/tool highlighted.
Restarting the machine helps, but that seems a heavy handed solution to the problem.
*With the exception of the 'Activities Overview' item