Jonathan suggest here: Xcode Includes .xib files that have been deleted! that cleaning all targets and empty the caches will fix the problem with Xcode including deleted .xi
I had some problems with Xcode 5.1 crashing on me, when I opened the doc window.
I am not sure of the cause of it, because I was also updating docsets, while I opened the window.
Well, in Xcode 5 the modules directory now resides within the derived data folder, which I for obvious reasons didn't delete. I deleted the contents of ~/Library/Developer/Xcode/DerivedData/ModuleCache and the ~/Library/Preferences/com.apple.Xcode.plist and everything then seems to work, after I restarted Xcode.