SEF friendly activation leads to wrong redirection and no more home function

[Pyrrus]

Hi there,
I have a problem with activating SEF friendly URL in Joomla.
When I do this and go to my main domain www.baby-naturwelt.de i makes a redirection to www.baby-naturwelt/Shop-DE/ which leads to an error. Deactivation SEF friendly URLs solves this probem but leads another problem: when clicking on the shop logo i leads not to the homepage but to the page you are already on. Can somebody help?

Virtuemart 3.0.7
Joomla 3.4.1