As you might have noticed that there are problems in the Microsoft Outlook CRM clients after the October 2017 Security update of Microsoft.
At a certain point, Outlook was unable to display the CRM ribbon in Outlook menu, see screenshot
below: "Waiting for a page to be retrieved from a Microsoft Dynamics 365 server.."
To fix this issue, go to this link.
In my case I am using Microsoft Outlook 2016: create the following registry key:
[HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Security] "EnableRoamingFolderHomepages"=dword:00000002
And after closing Outlook and starting up Outlook again, CRM is succesfully loaded and working again.