Its an odd line, especially since bottom shows signs of indentations
Run an anti virus scan and malwarescan
what are rest of specs of the PC?
Try doing a clean boot and see if same thing happens after sleep - read instructions carefully and make sure not to close all MS services or PC won't boot correctly - https://support.microsoft.com/en-au/help/929135/how-to-perform-a-clean-boot-in-windows
if it fixes it, its possible it is caused by a startup program, need to re add them slowly to find what is causing it. Then we can work out why.