The Boeing Portal support team was able to help a little, but they have no documentation on how your IE11 should be setup to access their Exostar and Boeing Portal sites.
Some of the errors we were seeing were a black page after we clicked on the Boeing Portal link in the Exostar MAG page and then some people would get to the portal but then get a login screen any time they clicked on a link, like the REDARS/EID Drawing search window.
There also seems to be a new requirement to setup security questions. For people with problems this page may come up over and over.
For the record, we are running x64 Windows 10 Enterprise with Prizm Plugin 10.3
Here are the things we had to do in order to get full Portal access to work again.
Close all your IE Browser Windows
Open one new IE Browser Window
Go to TOOLS – INTERNET OPTIONS
Under BROWSING HISTORY – Click DELETE
Check ALL boxes Except for Passwords reset and the top checkbox for “Preserve favorites website data” – Click DELETE
Click on the Advanced tab and press both the reset and restore advanced settings buttons
Click on the Security tab
Click on Trusted Sites
Click on the Site Button
I have my security level set to low, but it will work fine set to Medium
This will not work until you REBOOT!
Some users reported that after this they need to attempt the login 3 times before it worked.
If you login fails, close all the windows and try again two more times.
If all else fails, Firefox works fine. We use v42 and v44 on Windows 10 x64 with Prizm 10.3.
Update - 10/19/2016
If Firefox still doesn't work we found that for a few people, uninstalling firefox and then reinstalling it will fix any issues. (Don't forgot to re-install Prizm after you do that!)
If you really get desperate, you can also try backing up and then re-creating the user's windows profile.