I am almost new to Debian. It is a great system. I get my work done in Debian very well. However, recently my Debian(sid) crash randomly and frequently. The problem is that the screen just get dark. And "ctrl+alt+backspace" doesn't work. "Ctrl +alt+f1" doesn't work either. So I just wonder if there is something like system log that I can check what is going wrong. I googled for while, but jet not a clue.