Ok several time now I have seen some strangeness with Ubuntu
I was in Mozilla reading a forum and the system just locked up witha blinking A., The one that indicates caps lock was just blinking and the mouse would not move. I had to power off the system.
Also I noticed that If I leave it for a while from time to time it is like there is a process taking up the cpu and wont release it. It takes for ever to do anything and the shutdown command takes for ever to come up. I endup powering off with the button.