Hoping someone here can help. Just unboxed my retina iMac yesterday. Base model except for upgrade to 512GB SSD. Here's my issue: During the initial setup screens, the computer locked up on the last screen which was activating/upgrading to iCloud drive. I had selected "not now" or whatever the no option was. Then I just got beachball forever. Finally shut down computer. When I started it back up, I went through the same questions but I couldn't name my home folder the same thing, so I basically was setting up a 2nd user account. I've since deleted that 2nd user account and gone with the first one. But now the computer takes over a minute to start up (it's pure SSD) and I get a black screen (not grey) with the apple logo and a white progress bar. The progress bar seems to start and restart and then I finally get to the log-in screen. Any ideas? Worried that's something amiss, especially with the beachball/freeze at initial setup. I haven't put anything on the computer yet, so should I reload Yosemite. If so, are there easy instructions on how? Thanks!