I use a 3 column Styling, but there are some displaying problems. Please see here: http://dasmobilewundzentrum.de/

The Maincontent with my Articles is displayed under the left sidebar, and the right sidebar ist displayed i nthe footer area. Whats going on ? Where is the mistake, i didnt change anything
Please Help !!!

Try deactivating your plugins and see what happens.

I did this already, but nothing happened, I think there is some complications with teh Plugi nPosts per Cat, but why ? Also if i deactivat this the widgets and everything will be under the site ...

when you say

I use a 3 column Styling

what do you mean?

the plugin 'post per cat' is causing the issue

3 columns mean left side widget area, middle is the content an right side also widget area.

ok but when i deactivated the plugin posts per cat, the issue is continue, i doesnt see the content in the middle and also not the widget on the right side

Double check your code in the content and sidebars and make sure you have closed all elements properly and/or not added some code that shouldn't be there.