Hi,

Sometimes, when I click on a window on the task bar, kde suddenly log out.
What can I do to prevent this ?

Thanks.

This sounds like a X crash - which is usually a bug in the graphics driver. Are you using Desktop Effects, and which graphics card/driver combination are you using?

For desktop effects, I have default options.
I just disabled it te see if this is related.

About the drivers I have an AMD 7790 with fglrx-updates drivers.
I used radeon before but I don't remeber if I had the bug with it.

Would there be a log I could check somewhere when it logs out ?

The relevant log files are likely named /var/log/Xorg.*.log. You probably want to look at the .old ones in particular.