One interesting case I had just the other day made me look like a fool. Just like in many cases, when you have issues connecting your Outlook to a CRM instance, there are a few basic steps you follow in trying to debug the issue. There is available a troubleshooting wizard at the following URL:
While this is helpful, one other place to go look at is the folder holding the logs on the client machine. these logs are located at various locations, depending on the version of Windows you are running and type of log you are searching. These are:
Configuration log files
|XP||C:\Document and Settings\user\Local Settings\Application Data\Microsoft\MSCRM\Logs|
|Vista & 7||C:\Users\user\AppData\Local\Microsoft\MSCRM\Logs|
Setup log files
|XP||C:\Document and Settings\user\Application Data\Microsoft\MSCRM\Logs|
|Vista & 7||C:\Users\user\AppData\Roaming\Microsoft\MSCRM\Logs|
All fine by me, but the situation I had had to do with the fact that the Outlook client was refusing to connect to my CRM instance while using IE it worked just fine. The Sync to Outlook was enable in the security role, and all looked just fine.
Finally, one of my colleagues stumbled upon an interesting piece of information. In the security role the users that could not connect had assigned, on the Business Management tab, under User Settings, we only had Read across the Organization enabled. Changing the Write setting to User allowed now all Outlook clients for the users of this group to connect.