Problem is our sites are not available while this happens.
You could find that your site is trying to download a file for you.
If you get that, don't bother to do a live chat with HG because it won't work.
They will basically tell you that there is an upgrade going on and it will take a few hours.
You need to open a ticket and ask them to change the public_html/htaccess file.
They need to add
AddHandler application/x-httpd-php5 .php .htm .html
Also check because they tend to cause all of the sites to point to the one registered. I have a reseller account, and all mine ended up showing my diet site.
They did correct it, but it took time, and lots of email.