When I try to click a tool in the search window, it doesn't allow me to click (shows a small stop icon) Why does this happen? Now I have to manually look over all the categories to look for a tool..... I'm using ArcMap 10.3
do you have a layer selected in the table of contents?
what are you trying to search?
the inability to do something, or the disabling of a tool, generally means a precondition for the tool to be enabled hasn't been met
moved to Managing Data in case there are other ideas