Would you mind providing following files from one of your problematic clients:
- NS_NAME.xml from %ProgramFiles%\Altiris\Altiris Agent\Client Policies
- AeXSWDPolicy.xml from %ProgramFiles%Altiris\Altiris Agent\Agents\SoftwareManagement\Software Delivery
Also, is there a specific update that caused clients to reboot or that happens after aeach patch cycle?
Thanks.