Vista - Monitor Message "No Signal Input"

I have a Laptop plugged into a monitor...monitor been working up until
yesterday. Upon boot-up, the monitor kicks in and I can see it loading WIN
XP. But as soon as the WIN chimes start, the monitor goes off line and then I
get a message saying "No Signal Input". Once this mode of action occurs, the
monitor switches to stand-by mode.

Laptop screen shows the continued WIN XP load. I have checked the Fn Screen
button, and this is not fixing the problem. Anyone able to shed light on this
problem.

I have entered the display properties window and have noticed that under the
settings tab, screen 1 states primary windows monitor and extend windows to
this monitor are both selected and greyed out. Screen 2 when I select extend
the windows to this monitor and apply/reset the functionality is deselected
automatically, I can not get these setting to stay as selected.

Any help would be appreciated

Thanks Tanya