Hi Richard,
The case is that usually scheduler service is running under System account which does not have its desktop and thus applications running on behalf of System account have no place where to show their user interface. Likewise, TestComplete started by the scheduler service running on behalf of the System account will start using System credentials and without accessible desktop. Due to this, TestComplete will be able to run tests, execute all actions that do not require user interface (e.g. start/stop service, do WMI calls, copy files, etc.) and start tested applications, but OS will prevent the tested application from showing its GUI and because of this TestComplete will not be able to emulate end-user actions just because of absence of the user interface. Just to be clear - the above behavior is not TestComplete's limitation, but the behavior of the OS.
You may consider starting scheduler service on behalf of the user that is logged-in into the test computer, so that OS can attach TestComplete to the existing user's desktop and provide it with GUI support.
I also recommend you to go through the
http://smartbear.com/support/viewarticle/11301/ help section.
