External Monitor gets no signal
I have a dell 6400 Inspiron 2GB ram and ATI Mobility Radeon X 1400 graphic card , windows vista upgraded to windows 7. I am using Acer X223HQ monitor as an external display with standerd VGA adaptor, I dont have DVI or HDMI port.I also use couple of other monitors at my work place. Everything was working fine however suddenly all the external monitors started showing no signal. I updated the graphic card drivers (currently version 8.3) as the advices on various forums and monitors but could not help. I also reinstalled windows 7 but no luck however reinstallation could make one change now I dont see "non generic pnp monitor" under device manager 'monitors' list. It detects monitor but I can duplicate display when I push Fn + F8 key everything is blank.when I press it again I can only see on monitor of my laptop. On screen resolution you can see again the monitors but can not change the resolution as it appears to be locked for external monitor and windows doesnot identify the monitor but shows in the list. I am looking for soultion.