Horizon in offline mode

I have no antivirus installed and it still will not go online. I have no idea what I have done wrong.
Pleas help me

Try this first, uninstall Horizon from your computer and download the latest version here Horizon
Reply back with results, if you need more help one of us Horizon Pros will be here to help you further. Good luck.

i am having problems installing horizon. i got to double click the installer and a window pops up saying the installer was unable to access the server please try again later. im running on media center edition 2005. i tried right clicking going to properties and changing the compadibility but no success. i searched an older horizon download it let me install version 2.5.4.0 but it is in offline mode. can someone help me???