Multiterm believes it is still installed but it isn't and I cannot reinstall

Hi, for a few days now (I think since the last Trados update) my Multiterm isn't working. At first merely the viewer in Studio didn't work and then Mutliterm when used separately wasn't opening anymore. It was showing a small non-existent preview window when I toggled but it didn't open. Now I tried to uninstall all Multiterm versions to reinstall it. I found all kinds of old versions and got rid of them. Now Windows shows no Multiterm at all anymore but it still thinks it is installed when I try to reinstall:
"Error - a newer version of Multiterm is still installed. You must delete the installation file of that version" or similar is the error message.

Does anyone know about this? THanks!