Hi. I have newbie question. I recently installed CentOS 6.3 64-bit on my machine. It seems like every 15 or 30 minutes or so, and always while I'm typing on the keyboard, either the system automatically logs me out, or the X server crashes. Either way, I have to log back in, and I lose everything I was working on.

I can't be 100 percent sure what I was doing exactly when this happens, but it seems to involve some combination of Shift or Alt or Ctrl key presses. I did turn of the 'Log Out' in 'Keyboard Shortcuts' which was CTRL+ALT+DELETE, but it still occurs.

Does anyone know why this is occurring? Is this a bug or a feature? Most importantly, how can I turn this off?

It seems that you press Ctrl + Alt + Backspace key combinations, which actually kills your current X session and returns you to the login screen (see here).

So can you once try this key combination on your running session for testing and check if it's causing the problem. However, one solutions would be to not use this key combinations.

Yes, Ctrl+Alt+Backspace is causing this to happen.

However, I use emacs (which stands for Esc Meta Alt Ctrl Shift) for editing files, and it's difficult not to inadvertently press this every so often.

Can I somehow turn off the Ctrl+Alt+Backspace feature so that it doesn't restart the X server?

You can do it from, System > Preferences > Keyboard Shortcuts

A keyboard shortcut may be disabled simply by clicking on the shortcut in the Keyboard shortcuts dialog and pressing the Back Space key. The selected shortcut will subsequently display a Disabled status.

(Source: See here)