Thumbnails Search on WordPress 3.4.1

Hi, i have a problem with WordPress 3.4.1

When i am writing a new entry on my blog, i take a image from galley for thumbnail but if i use search field in gallery, i get this message: “Hacking attempt…” or if i use date filter i get the same message.

Directly on gallery section i can search or filter the images without problem, but in entries i get that error.

this option its too important for me, how can i fix it?