>>SWAG - do your services depend on any other services, that may not have started yet at boot?
>>
>>What is different, either in how you start manually vs. automatic, or in the environment for those two different cases?
>
>I think the service is allowed to start. But, once in the OnStart() event, it tries to execute some code and that code may not be compliant with the security. Basically, I am trying to get a file version from a file on the drive. Maybe this is not accepted in that mode.

The Local System account needs to have permission to the file you are attempting to access. A quick way to check if this is a permission issue is to change the startup account to something like the Administrator account. If it works it's almost definitely permission related.

Is the file local? If not you will definitely not able to access it if the service is running as Local System (you would need an account that has the same username/password on both systems and you'd need to use UNC pathing - not mapped drive letters).