I'm not sure if this is any help but it might be worth a try.
I had a similar problem with setting cookies - IE was fine but Netscape wasn't happy.
The solution was to ensure that the domain has a leading dot ie:
setcookie(cookie_name,value,0,"/",".domain.com",0);
as opposed to:
setcookie(cookie_name,value,0,"/","domain.com",0);
Netscape is fussier (or implements the specs more correctly?) than IE.