One thing I would definitely note is to install the powermanagement-interface package on your machine. Suspending and hibernation sometimes will not work after installing and removing packages from the computer, and therefore it is recommended to reinstall this package if possible or really, applicable. I'm not stating that this will fix anything--I'm *only* recommending it. Open a shell. Type:
After entering your password, you will have root privileges over the next couple commands. This will help in ensuring you do not need to type 'sudo' before each administrative command. Now, type in:
You can type hibernate instead of suspend if you wish. If this command succeeds, excellent--the package is installed correctly and is working. If not, Linux should comment that it is not installed. In this case, type:
apt-get install powermanagement-interface
Press y, then press enter if prompted. Wait for the software to install. It is not required, but you can reboot the machine by simply typing reboot at the next blank line that appears, just to make sure that nothing'll get goofed up right after installation.
With the package installed, you should now be able to type "pmi action suspend", or "pmi action hibernate" (without quotes) at any shell to put the computer to sleep or to put it into hibernation.
Again, this is only just a recommendation.