I've installed Debian Wheezy. After a while (working properly without any problem), I see some problems while working in gnome. Some functions don't work properly, for example desktop icons are not shown anymore and the option in dconf is unselected and disabled. And also all the staring chars in power off options like restart, hibernate and ... are shown as a squares. After restart, gnome fails to start and only a terminal comes up. Startx command only causes a blank screen and only a mouse pointer to be shown.
Also pressing ctrl+Alt+F7, doesn't have any effect, but the other ttys work fine.
This procedure has happened to me several times during this week and every time I had reinstalled all the OS again. I was suspicious about my installation procedure or viruses. I did security updates.