Recently I have been having some really major issues regarding my screen of my Imac. Every once in a while the screen will either freeze up and leave me unable to click on anything, it will sometimes go completely black, accepting some thin white horizontal lines, or it will do some really random stuff as seen in the attached image. Anyone have any suggestions? My girlfriend suggested missing video drivers or a damaged hard drive or even a virus in the boot section of something or other (not exactly technically inclined here.) (it gets worse than pictured in the screenshot sometimes too) I'd appreciate the help Stu. B.