Problem with moving posts to trash

Hi, i connected some custom fields to built-in posts.
then i was going to move some previously created posts in trash, so i selected some posts and confirm my action.
Then i get some bugs, some posts doesn’t move from published status, sometimes i get messages saying posts already been in trash, sometimes they cant be moved or edited until i disable the plugin.

I cant understand if they give those problems because they were created before plugin installation… or something else.

Is there some solution?

http://wordpress.org/extend/plugins/simple-fields/