Because my downloads don't work that well / fast I changed the 3 available connections. Then I found a tab "file collection"?? (Dateisammlung) (I use the German language of LM Dateisammlung) this particular file was listed there too. After marking it and click on the big red X it did delete the file also from my incoming folder.

Still the website howtoheaven.com contains many very useful tutorials and guides! Especially for computer "experts" (don't know anything about computer) like me...

Duebel