I've got a Dell d830 laptop. Gutsy ran fine but Hardy keeps crashing every few hours. Sometimes the laptop locks up for a few seconds (non-moving mouse, stuttering music) and sometimes it totally locks up with the scroll- and caps-lock blinking.
Compiz enabled/disabled, no luck.
Wireless/no wireless, no luck.
Not using the touchpad but a usb-mouse, no luck.
I already have made a few changes to my xorg.conf (setting DVI to false) with no effect and I have installed the backport-modules.
Kubuntu kde4 Hardy seems to crash less, but I have also seen a kernel panic on there.