KUbuntu terminating login session on prolong idle time

[Serg Belokamen]

Hi All, 

I noticed that when I either lock the screen and live it like that for
few hours. 

Or just live the workstation unattended so there is enough time for the
screensaver to kick in and activate screen lock and again let it sit
like that for few hours; when I come back and try to log back in it
shows me the login screen and not the password prompt that it should to
unlock the screen. 

That is, it closes all the programs and logs me out. 

Is there a reason for that? how can I make it so it does not log me out?

It is a specially annoying when I have dozens of things open and I have
to re-open them again etc.

   Serg