I have created my own application service, however when the user logs off the application stops.

A. A. When a user logs off, a number of messages are sent. For graphical applications the messages WM_QUERYENDSESSION and WM_ENDSESSION are sent, and to console (character mode) applications the message CTRL_LOGOFF_EVENT is sent. If your application responds to these messages then it may cause it to stop. You will need to modify your program to either ignore or handle the messages differently. There is more information on this in the resource kit.