Shutdown automatically, damage my file

[Walkinraven]

I'm sorry. It seems not the bug of Ubuntu. I solved it by reset my BIOS settings.

But I still don't know how this could happen. So I write this note for record only:

My system works fine for years, till one day it halted and power off without any notice. It happened 2-3 times, so I decided to update my system to Ubuntu 13, hoping it will solve this problem.

After updating, the system could not even boot anymore. So I reinstalled Ubuntu 12.04, but still it could not boot. I repeated the installation 2-3 times, even with fresh install, it could not boot.

I thought it may be my hardware problem, so I run self-test from BIOS, it passed full test. So I have no idea about this.

Finally, I reset my BIOS settings to default, just last try. It works!

I'm very surprised: I set my BIOS after 1st boot with my new PC, then never touched it again. So how could this happened?

I guess it caused by some settings in BIOS related with boot, have been changed by some unknown accident.

No idea about this. But whatever I'm glad my hardware is working again, and it's not a bug of Ubuntu.

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My environment:

* Dell Latitude e6520
* Ubuntu 12.04 LTS with latest updates

It happened 2-3 times, the system just was frozen for seconds, and then power off. I thought it may be the problem of my hardware, but the PC passed all BIOS testing items (full testing).

It happened when I was watching flash movie (only firefox openning); It happened when I was coding with Eclipse (Eclipse, gedit) ... It seems to be some bug of Ubuntu itself, not specific program.

The latest accident damaged my coding work. When I was writting a PHP file with Eclipse, the .php file become invalid encoded.

I works with this machine and the system for years, it worked fine， till very recently. I don't know if it caused by some updates.

I don't know how to do now. I can't trust the system. Don't know when it will happen again.

I use only TLS edition for Stability, should I update to Ubuntu 13 to try my luck?