My monitor turns on and i can see the desktop for 3 seconds and then it goes black, but the power light stays on.. do u kno why?

Does your monitor go black because it went to sleep, does it turn off? Do you have any lights on the monitor to indicate what it is doing?

Also I would boot into safe made by rebooting the computer & tapping F8 when the bios appears. You should be prompted with several options, one of which is "Safe Mode". Choose this & report how the monitor behaves.

check your video cable ends for bent pins or debris, then make certain that they are plugged in straight and tight.

make sure monitor is vented properly and not overheating.

Could be a power issue. If it doesn't show anything at all then that may be the case. It may also be the display itself. It would be a costly repair so you might be better off finding a new monitor.

reinstall windows ur screen resolution is not accepted by monitor

The problem is not with your screen. Its the problem of Video Card of your system which is unable to send Video Signals to the Screen.

I've had a very similar issue on many Dell Monitors. Mine have been under warranty and they usually send me a new monitor, but I believe the issue lies with the power supply within the monitor.

I have the same monitor and it is only 3 month's old, the power lock button continues to fail and they have replaced it 3 times with the same issue, What a piece of ****!!!!

check both your power and video connections to the monitor, sounds more like a monitor power issue.
if the connections appear ok, but screen still blank, try connecting a known good working monitor from somewhere else and see if it works with your pc, if it does, your original monitor is faulty, if it doesn't, you have a pc video issue.

I start my computer and turn it on, and everything looks fine for about 1/4 of a second and then it goes black while leaving the power light green. I can only see the screen again after turning it off and on, but that's only for another 1/4 second. What's up?
I got my rosewill flatscreen as a hand me down from my father. I've had it for several years now. Was working fine until a month ago. When I turn the computer on the screen goes black after 1/4 of a saecond. I have to turn it off and on anywhere from 10 to 20 times before it stays on. I have checked all plugs to the computer and outlets. I have absolutely no idea whats causing this.