Sorry, I missed that you mentioned it was a laptop.
Try this. Power off, and vacuum the vents to see if heat/clog vents is the issue.
Bob
I've had this problem for the last 2 weeks now and its really starting to frustrate me so if anyone can shed any light on this it would be most appreciated. Basically i'm finding these strange purple lines and marks on pictures and menu tabs. These marks seem to come and go completely randomly and they change size portionally to a picture if you zoom in on the picture. I've run norton and several other antivirus programmes but they've pickied up nothing. I've saved screenshots with the purple marks but when the computer is fine then the marks are not on the saved images. Please somebody help me out as this has become a real hassle,thanks.

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