How to determine the desktop type??

[C++ Programming]

Hi Gurus,

I have a simple application, which pops a message box if it is invoked in a pre-logon mode (i.e. when the system displays the login screen).

How do I get to know if the application is invoked before the user is logged on??
I tried using GetProcessWindowStation() - but this doesn't help.

NOTE: The application will be invoked from a service.

Thanks in advance.

Sunil