First, what type of monitor, (i.e., CRT, TFT)?
Have you tried the monitor on another machine?
If the monitor has analogue controls, try adjusting the horizontal and vertical size controls. Sometimes they become 'noisy' and moving them to another position will overcome the problem.
If it really is frame collapse, it tends to mean it's time for a new one, especially as the cost of new will probably be cheaper than a commersial repair. Common causes are defective frame chip or faulty HT stage, neither of which are considered diy. Try running the monitor at a lower resolution. Does the fault still happen or does it take longer to occur?
