Q: the screen just flashes with reds white blues &black, the only way to close it down is to switch off the main power.
A: It is sensible to plug the computer, screen etc into a 4 way suppressor block and turn of the plug on the wall when not in use. This will force all components off and save electricity as otherwise the monitor will usually draw current in standby mode http://www.trilogicuk.co.uk