You would need to uninstall any other MySQL instances and find any my.ini files and delete those also except the one in the \xampp\mysql\bin folder.
System is usually related to IIS or World Wide Publishing and it's associated programs.
You will need to disable these Windows default web servers before you can start Apache.
See if this IIS Forum topic helps:how to turn off iis 7
These search results
Let me know how you get on.
The latest XCPv3 versions can be found here:viewtopic.php?f=16&t=48932
Download and extract all the files and folders from the archive file into the xampp installation folder and overwrite when asked then use this latest version instead but close any other control panels you may have open.
This latest version has more features and more detailed reports in the log window.