OK, I added axiomaudio.com to my trusted site list and now the login seems to hold. Posting from Windows for the first time in... well, a long time.
I had to turn off the "require https on all sites in this zone" option (IE wouldn't add http://www.axiomaudio.com
otherwise) which I didn't like, but IE did let me turn the option back on again and I could still access the Axiom site via http... which makes no sense.
Just in case I removed axiomaudio.com from the trusted sites list and went back to my Linux boxes.