The problem is most likely a capacitor inside your monitor, they burn out after a while, so you might be able to fix it by replacing the bad one. If you're lucky you can spot a bad one by checking if the top metal flat is bulging.
For reference you can look at this link, the second picture shows what I'm talking about: http://www.pcstats.com/articleview.cfm?articleID=195
Whiteouts and blackouts can also be caused by other components, so replacing the capacitor may or may not fix the problem.