I don't know if this is it or not, but according to Netscape, the domain in cookies should have 2 "." (dots). So, instead of:
setcookie("AgentID","$ID",time()+1000000,"/","jdwebdesign.com","0");
it should be:
setcookie("AgentID","$ID",time()+1000000,"/",".jdwebdesign.com","0");
Give that a shot...