[other] Looking for help to diagnose hard freezes

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http://ubuntuforums.org – Hello, I have a HP computer which used to freeze from time to time with 12.10. Now, it does so almost every night with 13.04. It rarely happens when I'm using it (three times in many months that I can remember) but it happens almost every night (this computer should be always running): when I'm back in the morning, monitor doesn't get input and nothing works: caps lock lights are stuck, SysReq+Alt commands don't work. I see nothing suspicious in syslog or dmesg. I've tried disabling all powersave functions. When it has happened with me in front of the computer, the mouse kept working for (Hardware)