title: Cannot access TYPO3 Backend and Install tool after upgrade from 4.5 to 4.6
body: <p>The server of my provider uses PHP 5.3.11, MySQL 5.1.55. Safe_mode is On. After upgrade source files from 4.5 to 4.6 version, removing cache files, I cannot see Install tool nor Backend. I see only blank page, with source code simple "1". When file ENABLE_INSTALL_TOOL is missing I can see only "The Install Tool is locked" message, that's all.</p>
  
  <p>I suppose some settings with PHP are not correctly set. Could you say, which settings I must check, step by step, to get TYPO3 4.6 work?</p>