During testing we runned into strange behaviour of the ribbon. It suddenly got greyed-out, but even stranger, the buttons still worked.
|Magic Ribbon: grey-out but clickable buttons|
|Error message in debug window|
|Security settings in IE|
Other side effect was that reaching the CRM application on server name worked fine, using the ip-address did show the mystery ribbon.
After some research this should do the trick and get it working again:
1) Add your CRM url to Local internet (Internet Options > Security)
2) Edit the settings in this zone -> Custom Level
3) Change in Miscellaneous section: Access data sources cross domain to Enable
Hope this post save you some frustrations and looking for solutions. The error might sent you to different path..
Happy debugging :)