I have read several threads about same issue, but with each thread there are different solutions, I got confused.
I have acer LCD screen connected to WinXP SP2 box, recently I experienced one of these message :
1- “Input no supported”.
2- “No Signal” and LED turns from green color to amber color.
This happened while the PC is working (i.e. not on reboot)
I thought the problem with LCD screen , I changed to other one , then same message appeared (“No Signal”).