I see that the editor icons aren't the standard ones (looks like Font Awesome ones). Is that an add-on you're using or have you done some code edits? If so try disabling the add-on or reverting the code edits so you get the standard editor and icons back, then see if the issue still occurs.
I haven't done any code changes, I'm using the flat awesome theme. Could try disable some addons when I get back home, but don't think I got any addon that would effect this as it's pretty much a clean install with XenPorta and a theme only.