If you have configured Blackberry Enterprise Server to use EWS for calendar access and free/busy information lookup, you may encounter the following errors in the logs of the BES server:

BES01_CALH_01_<date>.log
[20751] (03/26 00:03:31.030):{0x1CE4} {TestUser@example.com} WSUser::SetUser - Failed to create EWS::Service: HRESULT 80040154, EWS.DLL possibly not registered or mismatched in version

BES01_MAGT_01_<date>.log
[30000] (08/31 17:19:04.565):{0x24C} {Agent Startup}-CalHelperController::InitializeEws- COM Exception: Code = 80004003, WCode = 0000, Code meaning = Invalid pointer, Source = <none>
[30000] (08/31 17:19:04.565):{0x24C} {Agent Startup}-CalHelperController::I  ...