I have a problem opening pdfs from certain websites. This problem occured when I upgraded to Firefox 4.0. I usually opened pdf-files from Firefox in the adobe reader directly (not using the plugin). Now this does not work any more. When having set, that pdfs should be opened in the adobe reader nothing happens, when I click on the pdf-link. If pdfs should be opened using the adobe acrobat (in firefox) it works in most cases. But unfortunately it does not work everywhere. In some cases a new (empty) firefox window pops up, but nothing else happens. Is there anything I can do to solve this problem? By now I tried re-installing firefox, as well as the adobe reader, I disabled and enabled the plugins sequentially, but I did not find any solution!