Screen flickers due to hardware problems.
Cause:
The video data cable may be poorly shielded, or an older interlaced display unit (new technology uses non-interlaced) is being used. These situations can contribute to excessive eye strain and headaches after prolonged use.
Solution:
There is not enough information available to address this issue. Please contact a qualified computer technician or next-level support for possible replacement of the video cable (wired into display unit) or upgrading of the display unit and video card.
Try one of the following, in sequence:
1) Adjust or shift the display unit slightly.
2) Move the display unit to the other side of the desk and adjust it at a different angle.
3) Move the computer and display unit across the room or to another room away from fluorescent lights, laser printer, power lines in wall, or another device.
4) Refer this problem to a qualified computer technician or next-level support.