Drobox client open but won't start (Stuck in a loop)

Hello, I really need your help with this problem I have on Windows 10 ( Build 19044.2130) with Dropbox (Version 159.4.5870)!

Since a week, when I start my PC regularly I usually get a massage from the dropbox client after 10 minutes or so that it cant initialize correctly and needs either to restart or close entirely. In other words the client is not working properly. 

To fix this problem I did a fresh install of the newest version of the client. Now, after entering my credentials to login. I get to the screen where it says "done" or "advanced installation settings" (where you can choose your dropbox folder to be or what folders to sync with this device).

When I click done, the window closes and the client is running in my taskbar. (little icon). But it is grey, and when I hover it, it says "starting". When I open the client it does an infinite loading animation and says "starting" in the lower left corner (See pics).

When I click on the gear icon there is the option to "Login". But I did login before like 10 seconds ago. Also after a while the login window opens again and I need to type my login details in again. 

When I do that again I get to the same screen again. When I choose "advances settings" and click on either "Where Dropbox folder located" or on "Choose folder to sync", the buttons morph to an animation which is also an infinite loop. No explorer window opens or anything else, it is just stuck in a loop. 

Im clueless what to do now. I even followed your guide on how to do a clean install (clear all folders manually + clear registry).

What did I miss? (If youre wondering my Dropbox is in German)

Pic 1When I click on the icon Pic 2When I hover the icon in the taskbar Pic 3When I choose what folders to sync it shows this infinite loop and it wont open any window