I have asus p4s533mx motherboard. It has a 4x agp slot in which I placed Geforce 4 MX. I have been using this graphics card for 1 or 2 years. Now when I remove the card and plug my monitor onto the onboard vga controller, nothing gets displayed on the monitor. The light on the monitor gets blinking, but nothing gets displayed. The CPU makes usual sounds to indicate that proper boot has taken place. But nothing is displayed. What could be the problem ???