"An error occurred while processing your request.
Do you know why this occurring?
where did you download it from? sound like the problem is at the source if you downloaded from a corporate site
You could download it from My Esri if you have an organizational account that is under maintenance. You may also contact the local Esri Distributor for the desired setup media.
And if you are already using myesri, try a different browser. That sometimes helps.