Version:            (using KDE 4.3.4)
Compiler:          x86_64-pc-linux-gnu-4.4.2 
OS:                Linux
Installed from:    Gentoo Packages

Yesterday some of the keys on my keyboard (HP dv3) started to behave strangely.
Down arrow causes also new line, up arrow causes context menu to show up. Delete causes two ksnapshots to appear (seems like one on press, one on release, holding the key spawns many windows).
Page up and page down are also broken.
Each of these keys causes some undesired keypress in addition to their normal action.
Auto-repeat doesn't work with those keys.

It is not caused by user config, because it is same on a fresh account.
When I turn keyboard layouts off in system settings, everything seems normal, but delete doesn't respond.
It doesn't matter whether I set keyboard model to Evdev-managed, Generic or any model of HP. I'm using polish layout.

Now I'm running just plasma-desktop + kwin (without startkde) and everything is just fine.
I can set layout in system settings and it's still normal.

I will prepare a log from xev

Will you help me troubleshoot this problem?

Some system info:
glibc-2.11-r1
kernel 2.6.32 x86_64
X.Org X Server 1.7.4
x11-drivers/nvidia-drivers-190.53-r1
x11-drivers/xf86-input-evdev-2.3.2
x11-drivers/xf86-input-synaptics-1.2.1