Try the router set to WPA security. There are some other reasons such as failing routers and more but given so little details about the router settings I'll just note the one that helps the most.
Joined Weight Watchers online. Sometimes the site will connect and sometimes it won't. Other times after connecting I'm able to navigate for a while then it looses connection. I am not having any other issues with any other website.
Desktop operates Windows XP, Laptop is Vista. Firefox and IE on both computers. Linksys wrt54g v.3 router. Norton IS 2009.
I have tried turning off firewall and disconnecting router and plugging directly from modem to desktop with no change.
I'm not very computer savvy so any help would be appreciated.