Download = Page can not be displayed

I've set up several stores on different hosts but this one has me stumped. One of my friends have a store and everything goes fine during checkout until you go to download the product and the customer immediately gets a page can not be displayed. I'm having her check with her host to see if CURL is required and if so what the proxy host is but I am wanting to know if there is anything else that would cause this to happen? The zip is in the proper folder (download) and the attribute controller shows as valid so it's not that. We would appreciate any suggestions you might have. I believe she is using TWiki hosting if that helps.

Ok the host is Positive Vew Hosting, is anyone aware of any know problems with them. They told her they don't require CURL so we turned that off and still no change.