Can someone explain to me why I get white horizontal lines towards the top part of my screen? When I boots up they're not there, but after a while, I think more so after I opens up a browser, one sometimes more white horizontal lines appear. I tried to change the resolution but nothing happens. There is only one refresh rate of 60Hz and can't select any other. I've had the computer for about 18 months now - it's a Lenovo C320 all-in-one touch screen using Windows 7 Home Premium.
Sorry to say but it sounds like hardware. The contacts between the screen and the screen feeds are not making good contact so the pixels are all lit on the line . The fact that it is sensitive to time would indicate that the problem is there when the screen gets a little warmer. Try gently twisting the screen if you can and see if more or less lines appear. It unfortunately could also be the screen driver circuits that are misbehaving for a similar reason. Hope for your sake I am wrong!!!
Then it seems to be a hardware problem and will probably need a workshop visit. Just to be sure try your computer on a friends monitor. If it is the same then you have a hardware problem which is probably cheaper to get a new monitor rather than a repair.