After updating to Hardy I got a white screen of death upon rebooting. After some research it turned out that this was more of an Nvidia driver issue rather then Ubuntu. This may not have been the most correct way to fix it, but it worked for me.
Completely remove nvidia-glx-new
Remove nvidia-kernel-common (this also removes linux-restricted-modules), (I am not sure if step 2 is required)
Download the Nvidia beta driver that came out on April 10. You can get it here
hit ctrl + alt + f1 to break out of gnome
"sudo /etc/init.d/gdm stop" to shutdown the X server
sudo sh NVIDIA-Linux-x86-173.08-pkg1.run to install the driver. If it asks you to update you're xorg.conf file, let it.
Reboot. ("sudo reboot") You should now be able to enable Desktop effects. YAY FISH!
Note: I have a Dell XPS M1530