Sorry if ive posted in the wrong form.

Operating System: Windows XP

PROBLEM:"The computer will stay running and the monitor is still on but the screen just went blank (Black Screen)" The above has happened to me 5 times in the space of a month and a half. These are the steps i have taken and what i think the problem might have been. Trouble Shooting Steps:

1.Monitor> the monitor light stays green so it hasent gone into power save mode, also i know its not the monitor because i have recently change my monitor form my dell 17" to a flat screen and i still have the above problem.

 2.Computer> The computer stays running coz the power light stays on, so does the hd light and fan is still on.

 3.I thought it might be a overheating problem but its only after happening in the last month and a half. Also the last time this problem happened the computer was only on for about 5min.

4.Connections> all the connections are in perfect condition they havent been damaged. Ive checked all connections to see if there loose or broke.

5. OS> I have just reinstalled my operating system to see if that would help my problem but but its been 3 days since i did that and the problem returned.

 6. Upgrades> All the parts in my computer are the original parts i have not upgraded anything.

Any help would be greatfull. Thanks in advance.