As per subject. After i close FF - and it is no longer showing as an app in Task manager. When i try to restart it, it says it's still running and i have to ask it to close FF before it will open it again. AFAICS It happens randomly. It may be relevant that when using CCleaner, it often (randomly) hangs when cleaning FF internet cache and says FF needs to be closed when it is already closed and does not appear in task manager. If i ask CCleaner to close FF, the application hangs. Less likely perhaps to be relevant: i got a rogue change of Favicon on one site. I eventually deleted the relevant file hoping the Favicons would repopulate. Most have, but many haven't including hotmail and protonmail sites. There seem to be many causes/solutions to FF hanging but i thought these specific circumstances might make it easier to suggest what the problem is exactly and how to fix it. Thanks.