Background is missing after WP update

Hi! After i upgrade from 3.2 to 3.4.1 the background image its kinda missing.

In the Media Library the view link goes to:
http://www.punkska.com.ar/?attachment_id=3848

But when i click the link it changes into this one:
http://www.punkska.com.ar/punkska3/wp-content/uploads/2012/08/back01.jpg/

The problem is right at the end, the “/” in the URL. I dont know why, cuz the “/” is not supposed to be there.

This would be the right url:
http://www.punkska.com.ar/punkska3/wp-content/uploads/2012/08/back01.jpg

Any ideas?
What should i change to get the background working again?
Thanks!