Marketpress: Download page does not load / link not hidden

Fresh WP 3.5 install with MarketPress 2.8 and FrameMarket 1.4.9.6 Theme with Gridmarket as child theme.
When I purchase a download product I get an email with a link to the download page.
1. problem: When I click on the link in my email client Thunderbird the default browser starts (firefox) and then the page is offered for download - so the page seems not to be sent with mime type text/html.

Then I downloaded the html page and opened it locally.

2. problem: The page contains a download link to the physical location of the product (but in other postings here on the forum it was stated several times that the download link is masked)

Thanx for any advice