That's strange. Google shows this to be a Linux program, and you don't write anything about your using it. But you don't write that you use Windows either, of course.
So if it is Linux, go to the Linux forum.
If it is some version of Windows (higher than 95) Start/Run/Msconfig, go to Startup tab, and see if one of the programs started seems like agtray. Then uncheck it.
When I bootup my computer I get a square wrote in the center the word AGTRAY and there is a explanation mark also in the square.