Hmm, couple of things to check
When you run it in the classic, is the classic client on the server that has the actual NAS service running, it could be a wrong box type of issue
Also try changing the user/pass on the NAS service to a local or domain administration to ensure that it is not a permissions thing
Then lastly, the NAS service is a service that runs without needing a user to be logged in, for this reason messages etc don't work, so just check that the outlook component you are running does not open any screens or dialogs, when you run it on the classic is the send completely hidden with no mails popping up...etc?