PHP variables via SSL on IE5.x

Hi there, I am having trouble with posting a form to a php script through SSL on IE prior 5.5 sp1. It works like a charm on all other browsers. In IE it works without SSL, but when SSL is enabled, the browser pops up with a message that he is switching to an unsecure site and then all then displays a 404 error with the correct php file url inside the Adressbar. I guess the browser is somehow loosing all variables submited via post. Has anybody an idea how to solve that? I cant unfortunatelly provide a link, since I had to disable SSL on the productio server due to that error. Thank you for any help on that, Merlin