Have I read the related troubleshooter articles above before posting (which pages?)? No
Have I searched the tickets before posting? No
Have I read the documentation before posting (which pages?)? No
Joomla! version: (unknown)
PHP version: (unknown)
MySQL version: (unknown)
Host: (optional, but it helps us help you)
Admin Tools version: (unknown)
Description of my issue: What is an admin query string? Does it mean someone has tried to login to backend?