FWIW, I sent this message to Maximus at VaultNetwork.com on March 29th of this year:
ALERT: Multiple users (including me) are experiencing the following issue when downloading files:
When we click to download a file it just opens the file in the window
instead of asking us to save it. You should be able to see this if you
attempt to download anything from the Vault like a module, hakpak,
anything.
This started about 2-3 days ago or so. Here's a thread on the Bio forums about it:
http://social.biowar.../index/10745855
Something to do with MIME types or something like that?
I still don't know what the issue is. At the time I was getting the error on every download. I believe, now, it's only on some downloads.