screen goes black
My iMac 24" early 2008 was working just fine until yesterday when the screen turned off just like when it goes to sleep, but it did not light up when I woke the machine. The strange thing is that when I access the iMac from another mac it shares its screen just fine and everything seems okay. I tried restarting, logging off and on again, shutting down, unplugging and re-plugging but with no success. This morning I turned the machine on again and was surprised to see that everything was just okay. Then again, this evening after leaving iMac on for a while, the screen turned off again without iMac going to sleep. From what I can see it seems that when iMac warms up, something happens and the screen turns off.
Can anyone tell me what may be the cause of this and what would be the best remedy. I am reluctant to take the machine to a repairs shop since it may cost as much as two thirds of a new iMac to have this one repaired depending on the seriousness of the issue. With current sales of the E.O.L. models, it may cost just a bit more to actually get a new machine.
iMac 2.8GHz/Mini 2.0GHz/Mini 1.66GHz/iMacG4 1.25GHz/iPhone4, Mac OS X (10.6.4), Airport Extreme Gigabit LAN