Hello, for some time, the screen shows vertical stripes of lines that run through the screen from top to bottom (at an equal distance from each other horizontally). They are visible only in the case of contrasting colors. This phenomenon does not occur all the time, once the image is normal and once with stripes. Oddly the bars do not appear if the menu of the projector is displayed. The problem occurs when connected with an HDMI cable, the picture with D-SUB cable is OK. Checked on multiple devices and hdmi cables. Any ideas what it could be?