Invalid accept header: IE & external link

Hi! I'm getting an error similar to one describe by others using
Devise and Ajax in Internet Explorer: IE processes the controller as
"*/*" and the Http Basic Validation box pops up instead of having
Devise perform the validation.

The weird thing is that this *only* happens when clicking on a
separate link. If I copy & paste the link address, everything works
fine. If I click on the link, Http Basic Validation takes over

All gems should be up to date: Rails 3.0.5, Devise 1.1.7, newest
jquery-ujs in my javascripts folder.

Any idea why clicking on a link triggers such different behavior than
copying & pasting the link?