I thinkI've found it this is 1.0b1: HTTP/None: 401 Unauthorized here is 1.0a2 HTTP/None 401 Unauthorized IE doesn't like the 'HTTP/None: 401' it wants "HTTP/None 401 ..." ^ this fixes the problem 148c148 < append("HTTP/%s: %s" % (self._http_version, status)) --- > append("HTTP/%s %s" % (self._http_version, status)) 155a156 -steve