Pam, so I'm not the only one.
I purchased mine a while ago and gave up looking here but the other day it was really bad and thought I'd give it one more try. I've not tried Belkin but I was considering returning the device. I think I will drop them a line too.
I noticed 2 problems, tell me if this is true for you too. Firstly the iMac will only sleep after 3 attempts. That is to say, I tell it to sleep and as soon as it turns off it starts. On the third attempt it will sleep. A search here suggested the most common contributor to this problem was a USB Hub or device. As soon as I disconnected the hub, problem solved.
Next, I had connected 3 devices. A Wacom Tablet, a Sony Clié cradle and a Multi-Carder Reader. I notice the cradle failing, tried a search here and via Google. Nothing. I did notice similar to you that not all the green lights would be on, mainly the cradle (note the cradle was also powered). I tried moving them between ports and seeing if the iMac would recognise via the system profiler. The cradle would always fail. Note to anyone suggesting not connecting the cradle to the hub, i've tried this and tried connecting the cradle directly to the iMac. I still have a problem with this hub.
What is strange is that we both have the iMac G5 1.8GHz but I'm running 10.3, so it's either the iMac or the Belkin.
Sorry, I have not presented a solution, but noticed no one has replied to you and like you I feel left out. Just wanted you to know you're not alone and now you've given new steam to search further.
I hope to offer more later.
iMac G5 1.8GHz 1GB RAM Mac OS X (10.3.9)