The designated user is running the wrong (date) settings
The designated account is used to set some environment variables or settings. Most common is the Regional Options short date setting. A Windows operating system has two levels of environment variables: the system level and the user level. Know that user settings can override system settings.
System and user settings
An example of environment variables that may be set for both the system and user is the TEMP variable. TEMP may be set to C:\TEMP\system for the system, however, when the user SophieC logs in, it may be set to C:\TEMP\SophieC.
Other user specific settings such as the Regional Options, are stored in the registry. When a computer starts, the system defaults are loaded. The user level is only loaded upon request, for example, a login to a command prompt login.
The Microsoft knowledge base article KB257757 describes server-side automation of Office
The Microsoft knowledge base article KB288367 describes how to run COM components under a specific user account.