Your script looks fine, and this works perfectly fine for me in IE 5.5
Perhaps your IE 5 is bad. What you can do is you can try repairing it. Go to control panel | add/remove programs. Find Microsoft Internet Explorer and click remove. Then, click repair when the new window pops up and be prepared to restart later. Hopefully that'll work.
x = open('', 'newWin', 'width=800, height=600, resizable, scrollbars');