Hi gcolvet. Welcome to Windowsbbs!
What Operating System are you running and what version of Internet Explorer? Have you tried using a different web browser to access that particular website? If you are running IE7 have you tried running IE with no addons? (Start< All Programs< Accessories< System Tools< Internet Explorer no addons). Try deleting all your temporary Internet Files.
If those options don't work shut down all backround programs that are running in the system tray and try visiting that website with IE. Does the website show up in IE now?