Redmine

Whenever i try to move or delete an issue via the context menu I get the following error in production log:
@Processing IssuesController#index (for 192.168.78.34 at 2011-07-08 16:50:56) [GET]
Parameters: {"project_id"=>"ace", "action"=>"index", "controller"=>"issues"}
Rendering template within layouts/base
Rendering issues/index.rhtml
Completed in 178ms (View: 157, DB: 7) | 200 OK [http://web/projects/ace/issues]

Processing ContextMenusController#issues (for 192.168.78.34 at 2011-07-08 16:51:08) [GET]
Parameters: {"back_url"=>"/projects/ace/issues", "ids"=>["3"], "action"=>"issues", "authenticity_token"=>"xo76LMHz7DzOEjzGehQRmRHQhHJQElkrLoAd90RUMrI=", "controller"=>"context_menus"}
Rendering context_menus/issues
Completed in 44ms (View: 30, DB: 2) | 200 OK [http://web/issues/context_menu?authenticity_token=xo76LMHz7DzOEjzGehQRmRHQhHJQElkrLoAd90RUMrI%3D&back_url=%2Fprojects%2Face%2Fissues&ids%5B%5D=3]

Processing ProjectsController#ace (for 192.168.78.34 at 2011-07-08 16:51:10) [POST]
Parameters: {"back_url"=>"/projects/ace/issues", "ids"=>["3"], "action"=>"ace", "authenticity_token"=>"xo76LMHz7DzOEjzGehQRmRHQhHJQElkrLoAd90RUMrI=", "id"=>"destroy", "controller"=>"projects"}
Rendering template within layouts/base
Rendering common/error (404)
Filter chain halted as [:find_project] rendered_or_redirected.
Completed in 9ms (View: 6, DB: 0) | 404 Not Found [http://web/projects/ace/destroy?back_url=%2Fprojects%2Face%2Fissues&ids%5B%5D=3]@

This even happened on a fresh installation with just one project in it.

I use Apache 2 and Passenger. Running on standard port 80 with an own virtual host file. Everthing else is working fine. Please help.