Since I installed KDE 4.10, my screen/session locks after a very short time. I have never asked it to do this, and cannot find where to switch it OFF, I do not need my pc to lock.
I found the setting in configure desktop>hardware>display and monitor>screenlocker
Still mystified as to why KDE should choose to enable this setting without being asked to do so. Infuriating.
Imagine a class room or an office without it … IIRC this was announced on the KDE mailinglist, or even on kde.org.
Hmm I am not convinced, Knurpht. My computer is not in an office or classroom. Life is too short for KDE.org, or subscribe to a mailing list. I want my PC to behave as I want it to, not how someone else assumes I should have it behave, in a situation in which it is not going to be used. Office/classroom workstations will always be set up by a sysadmin, who will enable the session locking. Perhaps if it is considered REALLY necessary, on the lock screen should be an option ‘disable screen lock here’ with a button?
On my wife’s school teachers are told to logout from their windows sessions as soon as they leave their desks, and not to enter passwords when pupils can see it. She uses her openSUSE laptop with the lock feature. A “disable” button on the feature? Mmm, you found it, haven’t you, with all the other settings in a nice searchable screen.
Imho, it is not a choice of KDE but of openSUSE maintainers. Not sure, but I think they enable it by default. I’ve upgraded to KDE 4.10 at Arch Linux and figured out that there the screenlocker is disabled after installation.
But it is really not a big deal to disable it with “configure desktop”. It is not worth the excitement. 
This could very well be a decision at distro level. I just went where I suspected the option to be, it was there, I unchecked it, done.