Importing posts from wordpress.com messed up the design of the them

Hello everyone, i have an issue with a wordpress instalation.

For a while there i used to have a blog hosted on wordpress.com. After a few weeks 3 friends joined me and we used to write there for a while.

At some point i decided to move to my own domain with my own instalation. I exported my posts/comments everything related to me as author and moved to my new instalation.

A few days ago one of the guys that used to write with me on wordpress.com decided to join me. So i didn’t want his old posts to go to waste and i exported them from wordpress.com and imported them on my instalation. Now when viewing single.php on one of his posts i imported from wordpress.com the design is screwed up.

The footer is in the sidebar and the sidebars are under the post.

Do you have any ideas what it might be or what can i do? I’ll post a couple of screenshots:

My post written on the instalation:

https://i27.tinypic.com/taskgg.png

The posts imported from wordpress.com:

https://i27.tinypic.com/2lwaj4o.png

Thank you.