Fairly certain its a certificate problem. I had a untrusted certificate error when I initially went to the browse CDLC link. I selected trust site and continue anyways and it went to a login page. I tried to browse the catalog again and there was a momentary popup in the address bar showing red (indicating a certificate error) and then back to the login screen. Tried several times with the same results sans the initial certificate error warning. Using Windows 10 64 bit and IE 11.0.31. Works with no issue in Chrome.
