Pc not sending signals to monitor

[skymode]

Hello,
My pc is not giving signals to the mointor when i unplug the vga cable the monitor starts ( saying not connected to pc) but when I plug it back the light of monitor start's blinking and monitor does not start it happened when I installed new windows xp with sp3 and possible solution ?

 

[xroe]

Are you using a video card, if so, make sure that the vga cable is plugged into the video card's vga output.