Is the install succeeding on these 100+ computers (is KB947319 listed in Add/Remove Programs if you show updates or does it appear if you show update history at microsoftupdate.microsoft.com)? What happens if you install KB947319 manually on one of the problem computers, then reboot? Will Altiris still try to send the patch?
There are also the typical ideas of checking for viruses by performing a full scan (update could be trying to touch infected system or program files), running a Windows Installer repair, etc. If the install was successful, I would tend to blame Altiris; if it's been unsuccessful, I would tend to blame Microsoft.
Does this help at all?