Using Baan on windows 2003 server I need to execute a session from the command line and later from a service. The session does not have a UI.

Tried

ntbshell -server <session>

but I get 'link_shm: Cannot link to shared memory (error no 0). Check whether shared memory is loaded.' in the event log.

If I try 'ntbshell -ba <session>' I get 'manually connected' returned in the command window.

Baan is working perfectly from bw. Can you please give any guidance to locate the problem?

Always search before posting, this has been discussed already.
See this post for an example for doing what you want: http://www.baanboard.com/baanboard/showthread.php?t=15520&highlight=start+session
Basically you call the bw.exe with the .bwc file and the session as parameters,
make sure that the bwc config has the password saved.