Well, it's not so much an error as a behavior.  I can click on the link for the file once, and the download status bar appears.  But then it looks like a tug-of-war between taking 5 minutes to complete, to 5 days, then back to 5 minutes.  It's almost as if Renderosity didn't want to let it go.
It looked strange to me, too.

I'm not sure how many download attempts are normally given per order, but after the reset and one attempt, any subsequent attempts to download gave me the message:
You have exceeded the maximum number of downloads allowed for this product.

Is the maximum one (1)?

I'll try purchasing and downloading another file in a day or so and see if the same problem arises.  For now, though, I'm unable to download this order.

Rob K.