Unable to start a meeting

Hi

I tried to log into a meeting today through a link and then clicking on launch meeting but it would not let me join. It was no problem to join through the phone though and eventually it worked through "join from your browser".

I then tried to set up a meeting to test whether I could join. I set up a meeting on the webbrowser but every time a windows opens with "Start new meeting? You will have to leave this meeting to start the new meeting" although I do not have any  meeting open. If I want to start the meeting through the Zoom client the start button for the meeting is greyed out. 

I checked all plugins and extensions. Also downloaded last version. 

Anyone got an idea how to remedy this problem?