Sounds like a Config-Reader issue; Your hardware has not been identified by the SunMC agent setup properly.
A few things cause this.. Newer hardware that could require a supplement (or older version of SunM).
Messing with the boot banner can cause confusion in identifying the hardware (rare, but it happens).
What version SunMC are you using, and what platform are you running it on?
On the info tab, it tells you what it has identified the hardware as .. something similar to what is displayed by the 'uname' command.It is under the "Entity Family" field in this tab. What does it say there?
See the supplement docs, for which ones might apply here : http://docs.sun.com/app/docs/coll/810.3
iMac
Also, below is the details on the 3.5 supplement, including what are the packages, and which systems are supported. This is included as part of the 3.5 distribution, and is referred to as Deskop Add-on in the installation script.
http://docs.sun.com/source/816-7916/Chap1SunMC35_3.html
iMac