This unfortunate phenomenon is known as mura – a word that comes from a Japanese term for unevenness. A quality TV or monitor factory is not likely to ship a screen with a mura defect, but according to Bruce Berkoff of the LCD TV Association, mura effects often appear later in a screen’s life as the result of an impact to the screen – an all too common occurrence in laptops. “LCDs are like a glass sandwich that is soft in the middle,” he says. And a smack to the screen could be enough to compromise one of the screen layers without actually cracking the glass. That would disrupt the light path and make the screen appear brighter or darker in one section.

Unfortunately, this is one of those situations where the fix could be more expensive than a replacement, especially with an older machine. Repairing a laptop screen can cost thousands, which could probably cover most of the price of a new computer.