I've a Toshiba Satellite Pro U400 with Ubuntu 11.10. Very often when I'm working on the pc reboots itself, or close all programs and return to the login screen. This is very annoying, often I lose my job I'm doing, sometimes I make bad figures while projecting slides or movies in public. What happens is that with Unity 3 with Gnome, so I do not depend on these. I also checked the log files but with little success because I can not interpret them the best. Can you help me solve this serious problem? thanks. Roberto