I bought a new samsung s24d360 monitor. After a few hours of usage, some horizontal line appear. They are discolored(not white or black). The issue can be solved after opening and closing the monitor but after a few hour these same line reappear. I tried to screen cap the desktop but the image doesn't show these line. I check the vga cable and updated the drivers. Computer specs: amd-fx 6300, 8bg ram, gtx640 and windows 8.1.