Hi guys, A strange problem cropped up yesterday-i have a riMac running el Cap. Now, when I go to reboot, the computer chimes, then gives a black screen for a LONG time. Eventually, it gets to the Mac OS login screen. I tried to get it to boot into Windows 10, without success (also, holding down the option key for so long wasn't fun). Any ideas? Everything worked fine up til now. The only thing that happened yesterday was that I deleted stuff from the desktop, as my startup drive was full. I have about 500GB free now, and I'm sure I didn't delete anything critical. Thanks!