I use JoomSEF 3.4.2 in my shop beeindruckt.com and have an error if a customer wants to order (bestellen) any item. If you call the shopping cart (Warenkorb) and sent the order via the button "Zur Bestellung" you will be directed to the wrong page.
The pictures of the startpage are above the normal order - what is wrong.

The displayed URL is (you have to put a item in the shopping cart first to test it):

http://www.beeindruckt.com/index.php?page=checkout.index&option=com_virtuemart&Itemid=179&redirected=1&Itemid=179

If you delete the last part from the URL "&Itemid=179&redirected=1&Itemid=179" you will see the page like I want it to be displayed.

Right page:
http://www.beeindruckt.com/index.php?page=checkout.index&option=com_virtuemart

Do anybody know if there is a setting in the global configuration which could help me? Or could you give me any advise to solve my problem?

Thanx for your help!