"Internet Explorer cannot display the webpage" for some websites

I recently bought a laptop with Vista Business. Since then, I cannot
access the some of websites. For example mymail.yorku.ca. I have no problem
with opening this page on my other computers with Windows XP with IE6 and
IE7. I tried to reset IE setting, enable SSL, lowering security and privacy
setting... Finaly, I wiped out this laptop and installed XP. No problem! Then
I formatted HDD, installed Vista again and got "Internet Explorer cannot
display the webpage"! There is no problem with the server. I use this page a
lot on ANY computers with Windows XP and 2k operating systems but i have no
access on Vista-based computer. Please help me!