I have a Lenovo T61 laptop (Intel® Core™2 Duo CPU T7500 @ 2.20GHz × 2) running Ubuntu 12.04
When I upgraded to Ubuntu 12.04 the suspend function failed. It would suspend, but then when I attempted to resume, I would get a blank screen and no key combination did anything, so I would be forced to re-boot.
However, one dialogue in searching for a solution gave me a clue, it mentioned issues with the Nivida driver 302.17
So, to fix you need to revert back to an earlier version (that had previously worked for me) ... specifically 295.49.
Instructions:
Download 295.59 drivers and get it ready to run
32 Bit i386
cd ~/; mkdir nvidia295.49; cd nvidia295.49/
wget -O NVIDIA-Linux-x86-295.49.run http://us.download.nvidia.com/XFree86/Linux-x86/295.49/NVIDIA-Linux-x86-295.49.run
chmod +x NVIDIA-Linux-x86-295.49.run
OR .. if you are 64 bit (amd64)
cd ~/; mkdir nvidia295.49; cd nvidia295.49/
wget -O NVIDIA-Linux-x86_64-295.49.run http://us.download.nvidia.com/XFree86/Linux-x86_64/295.49/NVIDIA-Linux-x86_64-295.49.run
chmod +x NVIDIA-Linux-x86_64-295.49.run
Disable nVidia Drivers from "Administration > Additional Drivers".
You can't install the drivers if X Server is up
Once the X server is down and you just have a terminal, run the installed
cd to the directory where you put it
cd ~/nvidia295.49
Now run it-
32 bit:
sudo sh ./NVIDIA-Linux-x86-295.49.run
or 64 bit:
sudo sh ./NVIDIA-Linux-x86_64-295.49.run
Work through the installer.
Reboot.