A reported bug in the Sun 1.3 and 1.4 JVM's can cause a cfhttp call on a valid URL to fail intermitently. A simple one-line addition to your jvm.config file will do the trick.
cfhttp on ColdFusion MX can Periodically Fail Due to Bug in Sun 1.3 and 1.4 JVM's (Macromedia TechNote, July 19, 2005)