Xcode 6.11 crashes when clicking main.storyboard

Hi there! I am very in into developing apps and I made a few apps last time before I reset my mac a few months ago. Now I installed the Xcode 6.11 for the OSX Mavericks (OSX 10.9.5). After that, I did all I learned from previous experience and suddenly the whole application crashed when I click on the main.storyboard to design my main menu on the left. I have tried editing the source code and everything but it does not work. Please help! Thanks!