Monitor not going out of Power save!!

Hi all,

When ever i turn my computer on, the lights come on the tower, the computer makes the windows Vista noises as though its starting up, but my Dell 24inch screen stays with the Orange (instead of Green) light. I turn the screen off then on again, get the green light and it says 1:auto detect "entering power save" and goes back into power save with the organe light. Sometimes i have luck turning the computer off at the power supply or the wall, leaving it for 5 or so seconds then turing the power supply or wall swtich back on and starting the computer up again. The screen works normally? It doesnt have any problems until i turn the computer off and the cycle may or may not start again. Sometimes if i get fed up with it, i come back 6 hours later and turn it on and its also fine?? Now this morning i am turning it off at the wall and the power supply and this isn't helping at all. I stopped using my computer for about 2 months because i thought it had had it. I think i have another monitor sitting around should i try plugging that in? i just think it may be a computer problem as well, because sometimes the lights on the tower are delayed in turning on? Dont know what this means if anything, but say i turn on the computer, everything starts up and makes noises, but there is say a 1 second delay for the tower lights to come on.

Can someone please help before i throw my computer onto the road!! The computer is about 1 yr 6 months old with pretty good stats. I was going to go get them but this Laptop that im on just had a problem :-S with the tabs and i couldnt bare losing all this typing and the frustration that would come with that!! :-(