I've just been upgrading a bunch of kit and decided to put an SSD drive into a 2010 macbook pro. The old disk drive had El Capitan installed. I put the drive into a 2006 iMac. When it booted I got a panic icon I have never seen before (see pic). I rebooted the iMac with a boot USB and installed Mavericks no problem. I'd just like to know what the panic icon actually means.