You might have encountered the following 'Applying Security Settings' failure error while installing MySQL Server (more precisely, during the instance configuration) for Windows.
This occurs because an older MySQL database (instance) exists in your system. To find where it is located, open the my.ini file in the MySQL installation folder and find '#Path to the database root' string. The line next to it specifies the default path to the database folder. By default this will be pointing to "C:/ProgramData/MySQL/MySQL Server 5.5/Data/".
Now remove the existing MySQL installation. Next, open the parent folder of the database location ( ie if the path is "C:/ProgramData/MySQL/MySQL Server 5.5/Data/" then open the folder that is the parent of "MySQL" folder). Here it will be "C:/ProgramData". Then delete the "MySQL" folder (with all its contents) in it.
Notes:
1. Deleting only the "Data" folder will also serve our purpose. But it would be better if you delete the entire location as specified above.
2. The "ProgramData" folder is a hidden/system folder. So in order to access it, type the path of the folder ("C:/ProgramData") in your windows explorer address bar and press enter.
3. Deleting the database will delete all the data stored in it. You may not be able to recover it.
Now install a fresh copy. You will see that it works like charm!
