I'm using SharePoint Designer 2010 against a SharePoint 2010 "Publishing Portal" site collection.
When I update an image in the "PublishingImages" library and check it in, I get prompted as usual that the item requires content approval and answer "yes" to the dialog and get a 404 page - page not found.
This only happens for the "PublishingImages" picture library. It doesn't happen in the master pages or page layout libraries.
Looking at the 404 URL: http://dev.testsite.org/PublishingImages/Forms/my-sub.aspx?RootFolder=PublishingImages
I noticed that it is using the forms page "my-sub.aspx". Looking in the "PublishingImages" folder "forms", I see one called "mysubmissions.aspx".
So, I copied the aspx file "mysubmissions.aspx" and created "my-sub.aspx" and all is well on approval linking from SharePoint Designer 2010.
That resolves it, but I don't want to do this for every site I build. Is this a defect in SharePoint Designer 2010? Or is it related somehow to they way the site was built out?