Problem with Session_Start() and Netscape 4.7

Hi ! I work on Win2000 Pro (MS IIE Server) with PHP4 running as ISAPI (works great by the way - despite many warnings here and there). Strange problem. I use sessions to manage member login etc. Briefly - I have a form, when the user can log-in. The result of this form (username and pass) are being sent to a php script via post method. This php script is the first one where a Session_Start() function exists. No problemo with Explorer... everything goes smooth. But the problem with Netscape is... in a moment of Session_Start() it tries to reload the page (I can see it trying to do so) but - there are missing data from the post method and the result is: "This document resulted from a POST operation and has expired from the cache. If you wish you can repost the form data to recreate the document by pressing the reload button." OK - after page reload it works fine again but... you understand I hope... Changing method to get instead of post helps a little bit as page reloading process does not bring an error but... it's ugly to send password with a URL... Nomen omen - any guess why starting sessions results with page reloading on Netscape ? No way to correct this by preferences tweaks... :-( Waiting your answer, Ziggi