Whenever you find the problem in Starting Zend Studio , and it is not giving any error then just do 3 simple steps                                    Close ZDE.  Locate the fileTypes directory under  {your user home directory}\ZDE\config_X.Y\fileTypes and delete it.(Where X.Y are Zend Studio version numbers,for versions of Zend Studio older than 3.5.x this directory is named:{Your user home directory}\ZDE\config\fileTypes)   Start ZDE again.