The monitor on my sister's PC after being on for a short time will turn all yellowish and greenish. I can still see everything on the screen, but the color is just bad. After a reboot it will be alright for a little while, but it's not long before it screws up again. To me it sounds like the video adapter, but I thought I would ask some of you more experienced experts before I tell her to go buy a video card. I can't remember the type of video card she has, but I can find out later if you need to know. I'm just hoping it's not the monitor.