Vertical lines on left half on monitor

[DAcl_12]

I am using an HP Pavilion Desktop 690-0073w computer with an Alienware AW2521H monitor. Two days ago I began to see some flickering lines on the left half of my screen. Now the lines are solid and do not go away unless the monitor is power cycled for a substantial amount of time. However, the return shortly after being reconnected to the computer. I have tried multiple cables and ports, all with the same result. What is puzzling is that the lines are completely solid unless something is moved from the right half of the screen to the left, i.e. crosses the middle. Then the lines on the left half reproduce the image and it duplicates it all the way across the screen horizontally, but it does so in a way to still produce consistent vertical lines. The lines do not disappear when I disconnect the computer from the monitor, rather they still appear to the left of where ever there is color variation in the middle of the screen. In the case of the Alienware monitor, it is to the left of the center popup that tells you it is going into standby mode or the Alienware logo itself. I have never had problems with the monitor or computer and am trying to determine if it is a software or hardware issue and if it is with the computer or monitor. The changing lines with something being dragged across the center makes me thinks software, but the fact that  the lines don't disappear when the computer is disconnected makes me think it is a monitor display issue. My drives are completely up to date. I did want to mention one thing that confused me. My roommate let me borrow his HDMI cables to see if it was the cable or display port that was causing the issue, and it was not. But when I returned the cable, the next day his computer started producing similar pink lines after previously never showing any lines at all. Just looking for insight into diagnosing this and then how to fix or repair it. Thank you!