My Dell Inspiron 1525 monitor display problem

[ksdwarki]

My Dell Inspiron 1525 monitor is not working and as such have been using an external monitor connected through VGA cable. Of late the external monitor does not come up at once. Pressing Fn+F8 shows the external monitor for a nano second and goes blank. The external monitor finally comes up after trying Fn+F8 for 25 to 30 times. Please help.

 

[Multipack]

Is it set to just display on your external monitor in Windows display settings?