Try upping your refresh rate in display settings - settings - advanced.
If that doesn't solve the problem, do you have any speakers (subwoofer, satlites etc) near the monitor. Something to do with the electromagnetic field given off by speakers can distort the screen.
Or, if you have a power supply (eg extension lead/multisocket) this can have the same effect.
Move any speakers/power supplys away from the monitor
hope this solves your problems