Finder not working and desktop completely blank in macOS High Sierra I was working 2 hours ago on a project in Xcode 9 and suddenly the simulators stopped working and the Main.storyboard looked awkward. 

I decided to restart the Mac thinking it would resolve the issue but now I can't work at all. The finder doesn't open, the desktop icons are missing, when I go to Disk Utility (after reboot with Cmd+R) at first I can't do the "First aid" to my internal HD because it says that is unmounted. 

I can mount it with any problem and then the Disk utility's "First aid" says that the HD is ok. When I restart the Mac again the problem is not solved and if I access to Disk Utility again the HD is unmounted again (yeah, a lot of agains, sorry for my english).

I'm trying to boot in safe mode now but I want to know if some of you have experienced this problem before while I wait.

Thanks in advance for any suggestion.
Ok...
For anyone searching for an similar answer reinstalling macOS (press Cmd+R on boot) [CALM DOWN BECAUSE IT WONT ERASE ANY OF YOUR FILES] did the trick.

In my case Xcode was failing too and after removing it and reinstalling all return back to normality.

Thanks.