freezing

Well, the situation is strange... I tried moving to KDE from GNOME and I even liked it but there is a weird thing. KDE crashes my laptop. Completely. After a few hours of using it it just hangs up upon some action, like a desktop switch or right-click on some icon in Konqueror -- in all cases it's some KDE-related thing. The computer crashes completely then. I can't kill X, reboot or even ping my laptop from the outside. Only power off helps. In GNOME, it has never happened, neither in FVWM-Crystal. I suspected arts daemon so I uninstalled it, but it didn't help.