Hello,
Thank you for posting in Q&A forum.
If you are sure that the problem is not with the screen hardware, then the gray grid lines appear. I suspect that the screen resolution may be set too low. I suggest you increase the screen resolution.
Excluding the influence of third-party applications, I suggest you open the computer in clean mode to see if the problem exists.
Outdated or damaged drivers may also cause this problem. Open the device manager, find the display adapter, right-click and select "Update Driver" to select automatic update or manually download the latest driver.
I hope the information above is helpful.
Best regards
Zunhui
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