MacOS – Xcode will not launch correctly; works correctly with another account on the same machine

I have an issue where Xcode will not launch. The blue light shows under the icon, but nothing else seems to happen.
I've already grabbed the latest version from the App Store and reinstalled, didn't fix the issue. Please help.

Log shows the following (two lines only, edited for easier reading):

Jan 19 22:11:15 Jason-McClurgs-MacBook-Pro Xcode[2089]: Unable to find either a
    loadable database or a Nodes.xml configuration file
Jan 19 22:11:15 Jason-McClurgs-MacBook-Pro Xcode[2089]: Error loading docSet 
     file://localhost/Developer/Documentation/DocSets/com.apple.ADC_Reference_Library.DeveloperTools.docset/:
     Error Domain=com.apple.DADocSetAccess Code=12 "Documentation set could not be read."
     UserInfo=0x400ac5340 {NSLocalizedDescription=Documentation set could not be read.,
     NSLocalizedFailureReason=Unable to find the database or 'Nodes.xml' configuration file.}