problem between IE and PHP

Hi all, I'm having a little problem with the interaction between php and IE. I have two ".php" pages. The first contains a form with the standard submit button. However when I come to push the button, I get a "ding" sound (standard error sound) and it seems like the button is deactivated. However when I try with my firefox browser, everything works fine. I then created a duplicate of the page, with no php and saved it as a ".html" file. With internet explorer and firefox, everything worked fine. I do not understand how this can be. Is Internet Explorer treated the php differently? Any help would be greatly appreciated. Cheers Phil