At the moment you are affected by a bug in the SNTC portal that was caused by a recent required security change in the process of authentication to the Portal.
Please monitor the following bug until it is in resolved state
https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvr54849
A possible workaround but not always is to ensure you clear all cache and use Chrome Browser in incognito mode.
This is a severity 2 bug and the developers are working hard to get this resolved