Update Problem – Looking for solution

Hello friends, I am using 1 password for quite some time now but now I want to update it, and my system won't allow me to do it.
I always get the following error message on my screen:

Setup
Setup has detected that Internet Explorer (or Windows Explorer) is currently running. Please close all instance of – Internet Explorer – Windows Explorer Then click OK to continue, or Cancel to exit.
Alternatively, you might want to restart your computer, and try again. OK Abbrechen I don’t know what it means when I don’t even have the internet explorer installed on my system. However I am using Windows explorer on my system. What should I do to get rid of the error?
Your suggestions are awaited. Regards,
John
