bbPress.org

ok, you need to eliminate whether it is a plugin or theme issue

Check other plugins

Check that no other plugins are affecting this.

Turn off all other plugins apart from bbpress, and see if that fixes the problem. If the problem is resolved, add back one at a time to see which is causing the conflict.

Check themes

If plugins are not the cause, then it may be a theme issue. Switch to a default theme, such as twentytwelve, and test.

and come back and let us know