After my reinstall of the malfunctioning BitDefender product I have had problems losing focus of the active window. After doing quite a bit of research I can confirm that it is the tray-minimized security center that is the guilty one.
It does not matter which application is the active one. All of a sudden you cannot type in text and notice that the window title bar has turned from blue (active) to grey (passive). You have to click the window to regain focus. If one alt-tabs immediately after losing focus the "Bitdefender Security center" is the first to show up. The problem is that this window should NEVER get the focus as it resides in the System Tray.
This is quite an annoyance as it happens several times a day.
The Build number is 12.0.12.
Markku