Seems like a bug in 4.4.18 Adguard now crashes and silently disappears from the gadget bar and you start wondering why you're seeing ads. Then go to Adguard's extension properties page and you see that it's toggle is still on, but you have to toggle it off then back on to get Adguard running again and showing again on the extension bar. This has now happened on 4.4.18 twice on one of my PCs and once on my other one. In earlier Adguard version this has never happened.