I usually don't check the Altiris Agent on my own PC (OptiPlex 7010) but happened to do so today where I saw that it hasn't ran either the full or delta inventory for awhile. Can't tell you exactly how long because I think I cleared the task history about a month ago when I was testing something. In any case, only antivirus inventory has been firing off as expected under my task history. Found the following locked thread where I appear to have the same issue Sally5432 came across.
https://www-secure.symantec.com/connect/forums/tips-troubleshooting-when-inventory-policies-dont-run
Nothing really stands out in my a.logs where I, too, don't see anything wrong with the Altiris agent and its additional plug-ins. This might not be related but I couldn't get to my desktop with RAAD from my second PC (said something like the Altiris Agent wasn't installed) and had the same problem with other OptiPlex 7010's I randomly tried getting to although not all of them.
My 7010 came with Win7 Pro which I used right out of the box unlike some of my other PCs where I installed the OS from scratch. Thinking there has to be software that's somehow interfering with the full/delta inventory tasks (basic inventory is being reported as usual). Was there any resolution to the original message thread?