Same problem here.
Thought I'd give elemental another try, and did a clean install. I get the same error message as the OP on launching the game:
"Failed to download data file. Please make sure that you are connected to the internet, have signed into Impulse, and that no firewall or anti-virus program is blocking elemental."
No anti-virus is running, impulse is up and running. I've tried multiple times, with the same result. Any ideas on what to try?
EDIT: When I shift-tab to the impulse side-bar, it shows me as not logged in even though I'm logged in under the impulse client. When I attempt to log-in through the side-bar, the message "An error occurred trying to process your request" appears. Some problem with the impulse login it seems.
EDIT2: The game loaded up while I was typing the original edit. Still not showing as logged in on impulse, but meh, it's working now.
EDIT3: Crash, "Out of Memory", then same error when I try to get back into the game - i.e., unable to play at the moment. Guess Elemental goes back into the "wait and see" bin - I thought these kinds of technical errors would be fixed by now.