Bugs in Windows app.
When running it causes strange behaviour in already opened windows. Sometimess you need several tries to switch between opened explorer windows for example. Or when switching from browser window to explorer window the focus changes, but the browser window stays on top for some reason. Or you need to click on explorer icon in taskbar several times to see the explorer window on top of somethimg already opened.
Most likely you have multiple Microsoft Visual C++ versions installed on your computer and the tracker gets stuck, uninstalling them usually helps. You can find Visual* in: Control Panel\Programs\Programs and Features