I recently ran into a CRM 2011 Outlook Client issue that I had not previously seen. In this scenario, the CRM Ribbon would not display while everything else worked in the Outlook Client as expected: could view the CRM folders, views, open records, etc.. Additionally, CRM was not throwing any errors so there were no errors written to the log files.
I tried several of the usual troubleshooting steps to include, deleting the Outlook Temp files, disabling unused add-ins, completely uninstalling and reinstalling the CRM Outlook Client……
When I ran out of things to try, I opened a ticket with Microsoft support and they let me know that they have seen this issue in relationship to a product called Websense. It appears that if Websense is enabled but does not have the latest version / update installed, it can interfere with the CRM Outlook Client. The fix for this issue is to ensure Websense is running with the latest update. If that doesn’t work then you will need to disable it.
I hope this saves you some time if you run into this issue.
Cheers
Donna Edwards 
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