Why is my 2007 HP V17 monitor screen flickering and going black?

I have an old  2007 HP V17 monitor attached with a VGA cable to an early 2008 Macbook running on OS 10.6.8 software  via a  DVI- mini connector (this is also my desktop computer). 

About 6 months ago, the HP display started going white and sometimes gray for a few seconds before the image would return, and a couple of times I had to unplug it and restart the Macbook before it came back.  I followed Apple's instructions for testing whether the problem was in the computer  (= resetting the system by resetting the Mac's parameter RAM and SMC), but the computer tested okay.  I then purchased a new VGA cable and DVI-mini connector, but the problem persisted. 

Today the HP screen suddenly went black (first time going black) and stayed black.   The power button stayed lit and if I pressed the Volume or Auto buttons, the "Volume" etc. message boxes did appear, so the device's backlight is apparently working and not burnt out (unless the backlight has nothing to do with the message boxes showing up, which for all I know may be the case).  However, the Desktop showed up only on the Macbook. 

I checked all the connections, removed the DVI connector and plugged it back into the Macbook several times, but the HP screen stayed black, so I removed the DVI connector in order to type this message on the Macbook.  Then, as I was writing this, I decided to plug it back into the Macbook one more time--and sure enough, the display is back! 

I love this monitor, which is the perfect size and ergonomic height for my setup, so I'd hate to have to replace it.  Can anyone tell me

1. Given the information above, what's the probable reason for the flickering and going to black?  If it's the computer, what could it be?  Can I solve this problem myself? (See above; I couldn't find any other ways to test the computer in the Apple articles database.) 
2. If not, could a monitor this old  be repaired?
3. If so, how much would repairing it cost, since buying a new monitor that I probably wouldn't like as much would cost upwards of $300?

Thanks so much for any advice out there!