Monitor going black

Every time I have had a Monitor repaired it's broken again a few hours after I get it back with a different problem. Unless the Monitor is Under Guarantee you can very quickly spend more in Labor to have it repaired than it costs to but a new one.

Col

Have you tested this monitor with another computer? if you have and the monitor works fine the problem may be the graphics card and not the monitor.
Check the physical connection of the monitor to the graphics card. Also you might want to check and ensure that the small threaded bolts on the graphics card mount bracket are not loose. If they are, the card can actually shift slightly in it's slot on the motherboard and then you have a very nasty problem on your hands. If those small bolts are loose when you check them, tighten them by using a small pair of needle-nose pliers. These bolts can loosen over time if you have a tendency to over-tighten the screw posts when you are plugging in and securing the connection for the monitor. Power down both computer AND monitor before you start physically checking the areas I described and just for good measure make sure you re-seat the graphics card in it's slot (if it's a stand-alone card).