System boots up but monitor goes blank with the message no signal

When I restart the PC, it appears that syatem boots properly; but when I try to log on, suddenly "No sigal message' appears and monitor goes blank. Some times, I am able to log on and after log on, when I click on any application, monitor again goes blank. I think the PC is still active during this as I had to force to power off to restart again. In safe mode, the monitor remains on for extended period and I have copied all the files from my C drive to D, just preparing for an ultimalte XP reload. I also did a complete virus scan in safe mode and monitor remained on during this period, I also ran 'Regisrty Mechanic' to clean up the registry. But same problem when I start windows in normal mode. This is happening for the last 3-4 days. I do not remember adding any new software or hardware. Today, finally I reinstalled the XP. During the entire process, the monitor was fine. Once after completion, when windows restarted and during logon process, again the monitor went blank. Could this be a graphics card related problem? Any help is greatly appreciated. I have XP SP3 running earlier when the problem started and now back to original CD with XP Home version ( 2005)

If you are getting no signal then it means that monitor if not receiving any signal from your video card. So, your card might have to be replaced. But before that you can try to boot into Safe Mode. Check if the problem persist, if not, then are things working properly in Safe Mode? If yes, then it is a problem with the video card driver that might be corrupted.

Thanks for the quick reply. As explained in my first post, in safe mode, I have no problem whatsoever using the PC for hours (when I was copying contents from C to D drive, it took almost 2 hours and during all this time monitor was receiving the signals). That intrigues me as if there was any problem with Video card, how was it working during the safe mode? Or may be due forced low resolution of 'Safe Mode' that the card it able to send the out put?

I was trying to get into safe mode to uninstall the video card. But now, the key board works when booting up to take me to 'Safe mode' but once the logon screen appears, the keyboard and mouse both are not responding! I am not able to try anything now ( pl note that I have reintalled windows XP and after that never been able to work on anything due to monitor going blank).

We were also facing similar problems with video card failing due to onboard software damaged. It could be worth if you check the video card manufacturer's website for fixes.