I was wrong: X doesn't hang up when slideshow is launched (alt-tab runs ok when the issue happens and I have also found a way to open gnome menu and so also a console), but it shows a grey screen with a blank rectangle on the left-top. Pratically when I launch slideshow the selected photo is not displayed at full-screen but it's displayed on the left-top of the screen and then it changes to black and the rest of the screen become grey.
I will change the title and the description of the issue.
I was wrong: X doesn't hang up when slideshow is launched (alt-tab runs ok when the issue happens and I have also found a way to open gnome menu and so also a console), but it shows a grey screen with a blank rectangle on the left-top. Pratically when I launch slideshow the selected photo is not displayed at full-screen but it's displayed on the left-top of the screen and then it changes to black and the rest of the screen become grey.
I will change the title and the description of the issue.