Hi, Last night I woke up and logged into my Mac (see signature) after 15 or so minutes sleep and resumed watching a video on YouTube. A split second later the screen froze and tiny faint squares filled dark areas of the screen. The mouse cursor was the only thing I had control of. I turned off the Mac, restarted it and saw this: Once the progress bar reaches halfway the stripes disappear however the Apple logo and bar do not return either. This is as far as it goes. I tried to boot into the recovery disk but the computer crashes and restarts. Text pops up before the Mac crashes: I then inserted a USB install drive of El Capitan in order to access Disk Utility, run First Aid and find out if there is an issue with the SSD. There wasn't. The vertical stripes persisted: EDIT: I forgot to add that I tried to boot into my Boot Camp Windows 10 partition, however all I saw was a black screen. No load up. Nothing. Next up was Apple Hardware Test on Disk 1 of the 10.5.2 install DVD. No problems were detected on the first short test, however the program stopped eight minutes into the long test. I waited 30 minutes but nothing happened. The stop test button was unresponsive too. The stripes are still there. I performed the SMC and PRAM resets, tried to log in but got the same results as before. Last step: boot into Safe Mode. It worked but the vertical stripes remains: As you can see, the stripes does not show up on white backgrounds and the bright portions of the screen. General performance is slower (more like dropped frames) and internet browsers slowly refresh each time there is movement. Viewing log files in the Console I see the name of the graphics card pop up - ATI Radeon X2000 (FYI it's an ATI Radeon HD 2600 Pro 256MB). Some log files are labelled spin, panic and (vaguely IIRC) hold or wait. Basically, I have no idea what's wrong. It's not the SSD. The GPU could be on the way out or the logic board chucked a wobbly. It might be a kernel panic too. What are your thoughts and what should be my next course of action? Your help and expertise would be most appreciated. Cheers.