Wallace wrote:
From the specs I don't see anything that would indicate that this monitor had any kind of sleep/hibernation or power saving modes.
According to the
manual (page 5), it does.
the monitor automatically reduces its power consumption when not in use. As the computer detects input from keyboard, mouse, or other input devices, the monitor automatically resumes functioning
Molly, thanks for the model number. I have a few questions and some suggestions.

The above OSD (on screen display) message is not listed in the manual exactly that way.
Is there any other text on the screen or is that all? More information could help troubleshoot the problem.
There is an option on your monitor to perform a Factory Reset (manual page 19).
You should go ahead and reset the monitor back to a factor state, just to ensure some internal configuration has not gotten messed up.
There is one option on your monitor (manual page 16) where you specify which type of connector to use (VGA or DVI-D). It looks like the default is to auto-detect.
You could change that option from "auto-detect" and tell the monitor exactly which connector to use. You can determine which connector you have by looking at the end of the video cable and comparing it to the image below.

If you determine that your connector is VGA, check the pins in the end of your connector to ensure none are bent. Bent pins are common and can cause all kinds of problems.
If you are currently using VGA and your computer's video adapter (on the back of the base unit) has the option to use a DVI connection, you should get a DVI cable and try that. DVI is a better way to connect and has a more crisp picture.
If none of these suggestions correct the problem, you probably have a failing monitor and you will eventually have to have it repaired or replaced. Repairs can be expensive so replacement is probably a better option.
Note: It might be a bad capacitor or it might be something else. Bad caps are easy to fix. They usually bulge or burst when they go bad. Bad ones can be easily detected and replaced with a soldering iron. I've replaced many of them over the years. A fair tech will probably charge $50-$100 to repair. A new monitor can be had for $150-$200 so unless you find someone to do it cheap, you're probably better off just buying another monitor, if it dies completely.