Use Encrypted Sessions is enable and causing the Dagent to be blocked from running some tasks.
1) Navigate to 'Start Menu > All Programs > Altiris > Deployment Solution > Configuration', this will open the Configuration Applet.
2) Select 'Options...' , then Select 'Transport' tab.
3) Uncheck the box to 'Allow encrypted sessions' and select 'Apply' to save changes. Restart the eXpress service. Wait for about 10 minutes for changes to take full effect.