I am running Ubuntu 13.10, Gnome shell - 3.10 on Dell Inspiron 3521 (bought almost one year ago). Initially it worked fine, but now laptop is suddenly freezing. Nothing works then, no mouse, no keyboard , no Ctrl+Alt+F1 or anything. The only option left is rebooting. What I observed is it usually happens on battery. Especially when I leave it off for a few minutes idle. I checked with Dell and got to know that it's not a hardware issue.
Has anyone else experienced the same?