The problem is most likely a defective or damaged SVGA cable. Check the flat screen’s monitor cable at both ends (where it connects to the computer and the flat screen itself - see picture below). Make sure the socket does not have any bent or broken pins. It may be possible to straighten the bent pins, however the pins are quite brittle, and do not suffer bending too many times (they just snap off).
Also make sure that the cable is not severely bent at the socket as this could cause an intermittent problem within the cable. If you found either of these situations, replace or repair the cable to see if the problem is corrected.
Otherwise, pitch the flat sceen and get a new one(assuming you've checked the drives, etc are correct).