Browse to the mysql dir and set permissions to write and modify on the myql dir.
To do that right click the mysql dir and select the security tab at the top.
Click the edit button just below the permissions window. Even though administrator should have access set to full control it might not. If you don't want to manually install using the tutorial I wrote, my installs were done via RDP and the tutorial takes that into account, you can try installing at an elevated level. Right click installer and choose run as administrator.