Originally Posted by m_w_sundaram
Thanks for attending the query...
Yes. I think you are correct. It is a hard reboot at any random time without even the OS switching off properly. How to identify the problem?
I get some messages from syslod often in the virtual consoles saying that something like "avc=...permission denied ... pid=... "postmaster"...device=sda2..."
Could you give some idea to rectify the problem....
Well, frequent candidates for random reboots are bad memory sticks or overheated cpu. So, I think that a good place to start is to use a livecd with memtest86 or to try to replace the ram sticks if you have some sane ones available.
You can also check the temperature of your cpu with any monitoring program. mbmon -A should tell you in command line, there are lot of graphical monitors as well. You should monitor it *while* you are doing heavy work (try compiling the kernel or launching some modern game or whatever, and see if the temperature raises too much while doing so.
I or someone else here could take a look at your dmesg output just in case, so if you can, post it to pastebin.com and put a link here so we can review it.