I believe it to be a common problem with numerous sources and solutions. I am suffering random system restarts with 8.04, also suffered the same with 7.10. My BIOS is up to date, my system is not over-heating. I shut off the application that scales the CPU frequency down. I do not know as of yet whether the problem is dependent on the laptop being plugged in or not. I love Ubuntu, I'm trying to teach myself C to further my abilities in my job area, but these restarts are very annoying. They do not seem to have a pattern, but the laptop does freeze right before it occurs and it's usually during regular use, browsing, torrenting, and a few other things. I am not running any intense applications or games. Currently using Gnome desktop. I do run Compiz-Fusion on normal desktop effects, plus a few I've employed on my own. Thank you so much for the time. I'll be happy to give any info needed in relation to the problem.
Toshiba Satellite P105-S6217
Nvidia GeForce Go 7300 Graphics card