An "overly sensitive" port doesn't sound very technical. Cox has issued me receivers and equipment with faulty ports, so that'd be my first suspicion. If the replacement box is still "sensitive," there are Contour receivers with outputs for component cables.
I can only suspect "sensitive" to mean an issue with piracy or encryption: High-bandwidth Digital Content Protection (HDCP). Perhaps the Aquos doesn't support the HDCP version Cox uses to protect content. I haven't tested but I've read an HDMI splitter would bypass HDCP.
