Outlook 2010 with Add-In gsyncit does not throw this error when sandboxed. Moving from Outlook 2010 to Outlook 2013 I encounter this error when running Outlook 2013 sandboxed when gsyncit starts and should be doing its synchronisation jobs:
Error = Internal error. Unable to cast COM object of type ‘Microsoft.Office.Interop.Outlook.ApplicationClass’ to interface type ‘Microsoft.Office.Interop.Outlook._Application’. This operation failed because the QueryInterface call on the COM component for the interface with IID ‘{00063001-0000-0000-C000-000000000046}’ failed due to the following error: Library not registered. (Exception from HRESULT: 0x8002801D (TYPE_E_LIBNOTREGISTERED)).
This error is known to the Add-In producer: Fieldston Software
However, I do not encounter this error when running Outlook 2013 unsandboxed. I checked the registry keys - I do have the correct settings - and I even added them in Comodo within the sandbox setting “Do not virtualize access to the specified registry keys/values” - but unfortunately to no avail… 
Any advice or suggestions are appreciated 