unable to save designer pdf after editing.

I use chrome?

Sorry, need to be more specific, I did compatibility settings in explorer because the completed pdf form is auto generated and populated from a web based application called Collaborator and the preferred browser is Explorer. The problem is in Designer es4, I insert encryption in the form on the submit event and need to edit and review all the time. To save time I save and open the form in adobe reader XI because the pdf viewer in es4 is too slow with bulky scripts.

I mean saving from designer to my local files, client side before the pdf is uploaded on server.

Thanks for your suggestions, i will close explorer before saving and see what happens

Such a simple thing creating so many problems. You were right, the preview window was the problem, so thanks again for responding! You learn something new every day!