Hi Jon,
Check the update rollups in CRM if they are to the latest version.
If they are to the latest version, you should go for reinstalling the connector. Connector should be uninstalled in the following manner:
1. Save all the maps that are being used in a folder
2. Uninstall the connector from Control Panel.
3. Delete the MSDI database that is created while installing connector.
4. Delete the "Microsoft Dynamics" folder in C:\Program Files (x86)\
5. Delete the log folder "Connector for MS Dynamics" file from "C:\ProgramData\Microsoft Dynamics"
Now reinstall the connector and it should work. Its mainly due to some cache problem.