MDS 2008 R2 UI not responding

I have installed and configured MDS 2008 R2 and am able to access the UI using IE 11 however it doesn't respond.

I can:

see the home page

access System Administration but do not have the ability to add a model

access User and Group Permissions but when I click on the green cross to add a user  IE spins for a second butnothing happens.

I have checked that 3.5 and WCF is installed. The same user is the the admin for the DB, the application pool and the web service. I have activated logging and no errors are showing. This has me stumped - any ideas would be appreciated.

Thanks