First of all I have my computer set up so that the moniter turns off after 2 minutes and sometimes when the computer hasn't been used for awhile usually overnight when I move the mouse the moniter turns back on but the entire screen is black (or sometimes there is a line of green bars at the top) or sometimes it won't even come back on at all. Any idea what could be wrong and what I could do to fix it?

It sounds like your system doesn't fully support hibernating using the advanced power management. Do you have windows controlling the monitor blanking or the motherboard's bios setting? Is just the monitor set to turn off or is the computer set to standby as well? If the computer is set to go into standby, you may want to disable it so as just the monitor gets blanked.

Here is how I have it set up, does that help?