"Application not found" error?

Win XP, steam purchased GSB w/ site purchased Tribe. (Which I got installed correctly, i think, it works I and I can fight tribe challenges…) Most challenges work just fine, occasionally the when I click the “download” tab from a challenge the game freezes. I can alt-tab to switch windows I find a windows error

"http://gratitousspacebattles/challengeupsell.php?&content=gsb-order

Application not found"

When I click ok, I can then closeout the GSB window (otherwise I have to force kill it) and restart and I pick another challenge. What am I missing? Clues?

EDIT - Ok, so NOW I notice at the top of the page ---- “get THE ORDER.” It would be nice if the challenges would only be available for the game/s I have purchased. I found this fustrating before I bought “The Tribe”, please tell me I am not going to be clicking on “order” challenges now just to be told I do not have the content.

PreTribe install I would at least get a GSB warning me that I did not have the content and the game would continue, perhaps this error is something different?

The game should only try and launch your default browser (that is apparently not set up right somehow on your machine) if you actively click the button to get the missing content.
Unfortunately, at the moment the challenge database has no idea what extra content is in a challenge until you try to download it (This information is in the binary challenge file, not the challenge database), which is why (rather annoyingly) I can’t put an icon on those challenges or let you filter them. The next time I overhaul the challenge system I’ll try and find a way to include that, for this very reason.

Makes sense. Thanks for taking the time to respond and address my my gripes. It is very refreshing to have a developer that continues to make improvments after the first month that the game has been released.