WAN; Partial Internet Access Question

My internet works but not completely. I can sign in to programs such as AOL Instant Messenger, Napster. When I go to aol.com or hotmail.com and try and sign in to my accounts, I cannot. I can go to ebay.com and search for items, but then cannot click on an individual item and see a full description. It seems as though I can access sites or “stuff” that is on the internet, or uploaded and posted to the internet, but when I try to access individual site databases (AOL’s email server, Hotmail’s email server, Ebay’s item database/server) I cannot gain access. I have had this problem for some time now, and am very curious on how to solve it. Any help would be much appreciated!

PC: Dell Latitude D600
OS: Windows XP Pro
Router: Netgear WGR614