Well, the discoloration would be possible if there is any hardware problem in your laptop. Most probable reason for such pink or blue color is the video cable that might have gone bad.
I do know that the cable cannot be changed by yourself. If you are comfortable with performing the repair on your own, you can buy the cable and replace it. But if you are not familiar with the tasks involved in the repair, I would advice you to take the laptop to a technician and get the problem solved.
If you want to be sure that it is not a software issue, you may perform the following tips -
1. Perform defragmentation and check disk
2. You may cleanup registry issues with Reginout Registry Manager.
3. Perform hardware reset. To do this, you will need to remove battery, cable and other peripherals. Then press and hold down the power button for 20 seconds. This clears out the RAM and discharges the residual current inside the laptop.
However, I do feel that this is a hardware issue and will need you to visit a repair shop to get it rectified.
Live....and Let Live!