I've seen this happen with web based email accounts, and sites that use HTTPS. If you are using a router, try bypassing the router (just as a process of elimination). I know with the web based email, it ended up being the router. If I remember correctly, it had something to do with adjusting the MTU setting within the router. However, before you do that, try it by bypassing the router first.
I have a Packard Bell i-Media 5267 P4 and my wife has an Acer laptop P4. I've just set up a home network and everything is fine. We've both got access to the internet, but my wife can't access her ebay account. She can get onto the website but she can't sign in.
Page keeps coming up, saying 'Page cannot be displayed'. She can access the account on the Packard Bell so we know there's not a problem with the site.
We probably haven't, but we feel that we've tried everything! Any help will be much appreciated.