OK -I have to admit to being pretty much stuck on this one. I have really been fighting the interface from the word go. From the top here's what I did.
After completing this and then fighting with PXE images for several hours, I then came back to the interface the next day to try and deploy the task on a new computer (I resorted to using Bootwiz to create a CD ISO).
Sadly when I now view the task I get the error "A Critical Error has occured on this page. Check the Altiris Logs for more information"
The Altiris Logs say,
Description: Unhandled exception on page
Any help gratefully received
Update: Cloning the task gives this the same error on both, so only resolution seemed to be to create from scratch.
Thinking on it -this happened after using the silverlight portal to drop the task onto a computer. Before that point the task was viewable and editable.