I run a Ubuntu 12.04 desktop in my office. I keep it usually running 24x7. When I came to my desk this morning, I found that the system rebooted at 23:52 last night. I could not find any trace of any malfunction which could have caused this reboot. I checked every file that had been modified after 23:00 last night, trying to find any suspicious entries, but I could not find anything.
This happened already once before (a few weeks ago).
My question: Is there any way I can get some diagnostic information in such a case? Can I turn on some debug/trace switch which causes the system to record more information as to why it reboots?