Check SiePortal (Siemens Support) for the latest Update (Upd) for your version of WinCC 7.5. Many "application could not be started" bugs are resolved in cumulative updates.
: If the computer name contains special characters (like underscores), the SQL instance may have installed incorrectly. You may need to uninstall both WinCC and SQL Server and reinstall them starting with a clean machine name. a basic application could not be started wincc 75