Installation stops halfway. Files not found and internal server error 500
The log file got me on my way after a tip from Brad Bell:


  'CDbException' with message 'CDbCommand failed during the SQL statement: SQLSTATE[42S01]: Base table or view already exists: 1050 Table 'craft_assetfiles' already exists' in ...craft/app/framework/db/CDbCommand.php:358


Removing the database and doing a fresh install solved the issue.