A software resource was pushed out to test clients to install a package (any program had this issue) and it would fail almost instantly, returning an exit code of -99.
In the Agent logs, the severity 1 entry read,
'AlternateLocation' attribute not found in the Task XML
The Altiris Agent was on an older build; it had not been updated after the Notification Server was upgraded to SP2.
Upgrade your Agents to the latest version, matching the Notification Server version. The build of Altiris Agent for Notification Server 7.0 SP2 is 7.0.3569.