Black screen as soon as the computer boots up and we turn the Daewoo l700c monitor on, the screen goes on for a split 2 seconds and turns black, hitting the auto button again the screen appears for a split second then turns to black.

How old is the computer? Make sure that the power light comes onto the monitor when you plug it in, should be orange and then turn green when video card syncs with it when PC is turned on. If you are getting black screen when PC is powered on:
1. Bad video card
2. Bad video cable
3. Bad monitor
1Solution: Try using a different monitor attached to this same PC and see if it works. If it does, then its the monitor, its cable, or its power supply. If it doesn't work, then its the video card or the video cable coming from monitor.