There are two possible solutions to this issue:
1) Set up HTTP authentication in the Workflow Server Extensions configuration. This will tell the Server Extensions to authenticate using different credentials. This option is found here:
Start > All Programs > Altiris > Workflow Designer > Tools > Server Extensions Configurator
Find the section called "Webservice Auto Invoke", click HTTP Authentication, and put in the username and password that will have the required rights to the .asmx files.2) Select the AutoInvokeDelegateService.asmx and WorkflowManagementService.asmx files in IIS Manager and set their authentication to Enable Anonymous access. Also make sure that Integrated Windows Authentication is not selected.
Altiris Workflow Solution 6.5