I am using a Raspbeery Pi 3 B (v 1.2) running Raspbian 2.5. When I boot up the Pi, my mouse seems to be working fine. It responds normally to movement. As soon as I try to open an application like Chromium or File Manager, I start to have problems. The cursor continues to move as normal when I move the mouse, but I am unable to click certain areas. Sometimes, I can only get a response from the taskbar. Other times, I can click inside an application. If I open a page from Help, in Chromium, it seems to work ok for a couple minutes. If I open Chromium directly, I immediately have this problem. Sometimes, the maximize window icon in the title bar of an application is the only part of that application and its window that responds to mouse-over.