I have a PC running Ubuntu 13.04 64bit, and I do weekly updates, so everything should be up-to-date. Everything is running fine, but sometimes, once-twice a week a complete reset happens. I think it must be software or hardware (perhaps Videocard) related, but I can't figure out what could be wrong. Can anybody suggest some ways, log files, where I could continue to search? By looking just at dmesg/dmesg.0 and Xorg.0.log I got nowhere. I cant find even a user application segfault. Any help is really appreciated.