Whenever my computer comes out of the screensaver, ubuntu restarts. I don't really know how else to explain it, it's just that whenever I get out of the screensaver, it takes about 30 seconds and then I'm back at the login screen.

I tried to find if maybe that's a security option, but I can't find any way to deactivate it. So I'm really not sure if that's a security option or if it's not supposed to be like that, but is there any way to change it?

Is it a reboot? Sounds really quick for 30seconds, if it has to powerdown.

Do you have any logs?

/var/log/messages at the time where your computer crash?

No, no, it's not the whole computer that reboots, just Ubuntu, if that makes sense. It doesn't go to the grub screen or anything like that.

I took a look at that messages file (I had never seen that file before, it's pretty interesting). Nothing is listed at the exact time it restarts. For this particular time, I made sure that I went into the screensaver preview and left as quickly as I could, prompting the restart. So, Ubuntu started to restart at exactly 13:34:40. The log, though, doesn't list anything at that time, just when it began to restart--

Well, I just updated to 7.10, and now it's working just fine. Thanks anyway, though!

I had the exact same problem with 7.04, works fine, screen saver -tries- to kick in, error that you can't read in time, then back to the login screen.

I ended up having to re-run the configuration for the xserver:

sudo cp /etc/X11/xorg.conf /etc/X11/xorg.mybackup.conf

and

sudo dpkg-reconfigure xserver-xorg

Which fixed a problem with my resolution not going above 800x600 and made the screen saver work as well.