Sidebar disappear in posts.

Hi!

My site has been working without problems for some days, but suddenly the sidebar is disappearing everytime I click on a post I’ve written. It doesn’t disappear when I click on the menu when I’m on the frontpage, so I can jump between the categories, but when I click on a post, the sidebar/menu is gone. I can’t remember that I’ve done any changes in the theme editor either. Does anyone know what the problem can be?

Thanks.

http://www.jorgent.com