I am new to these forums but have been using Ubuntu 12.10 for about 2 months now. It's been amazing do far, but for one problem. It occasionally freezes or locks down - even the time stops changing, the mouse freezes and all music stops. At first I thought it was a lack of RAM, but I found out with the use of a screenlet that it can do it at as low as 43% RAM usage. It's not happened enough to become a major problem, but it occurs on average once every few hours (but with no clear pattern). I am often not using very CPU/GPU/RAM intensive programs, or doing anything particularly strange. It just locks down and I need to reboot. I can't even do Ctrl+Alt+F2 to open the console and use 'sudo unity' or 'sudo startx' to restart the GUI, so I guess it's an internal problem.
Any ideas anybody? I would be very grateful to receive help on this problem, however small!