Hoping some one out has seen or recognises the fault condition I am experiencing with my laptop please. A picture of the screen would be easier, but I am not sure I can attach to forum message. Here goes my attempt to describe: the laptop happily chuggs along doing stuff , then all of a sudden, for no apparent reason, & as far as I can tell not after the same action or any other obvious pattern, the screen goes all chequerboard-like in colours (best way to describe it is like a carpet of multicolored vertically striped tiles). My first thought was the connection to the display, but it does the same on an external display. There are no associated unusual noises from anywhere (e.g disc). All the usual lights are on & the fans are running as they would normally.