Hi to all, I'm new to this forum, so I'm hoping someone can help me. Last week I updated my Macbook Pro to El Capitan and I wish I hadn't. I have a MacBook Pro, 15 inch , early 2011. - 2GHz Intel Core i7 - 4 GB 1333 MHz DDR3 - Intel HD-video 3000 384 MB Since I updated my MacBook to El Capitan, I noticed a problem: On completely random moments, the display becomes filled with lines or turns blue, black or light brown. When the screen turns blue/black/brown it freezes after a while and the Macbook automatically reboots. It also sometimes happens that the right side of the screen moves a little into the left side: when I move my cursor to the end of the right side, it enters the left side of the screen. This also results in a blue screen and an automatic reboot. I added some pictures and a movie to show what it looks like. Here's also a video: I'm not very technically skilled, so I had no idea what was wrong. I started googling and already tried the following things: - Erasing my hard drive in recovery mode and reinstalling El Capitan, this did not fix the problem. - Erasing the hard drive again and downgrading to Yosemite from an external SD disk. I managed to downgrade to Yosemite, but this also did not fix the problem. - I ran a detailed Apple Hardware Test, but the test found no error. - I reset my NVRAM and SCM, this also did not fix the problem. - I scanned for viruses and found nothing harmful. I haven't got the slightest idea what the problem is and how I can fix this, so I'm hoping some of you can tell me what I can try to fix this error. Thanks in advance.