I have been using Admin Console on my Mac for years to login to my ISY994i to control my home lighting. Don't recall making any changes but now I am getting the error ISY Finder:Not Found and I can't access the ISY to change any programs etc. Any suggestions?

It could be that the PLM is at end-of-life, especially if it's close to 2 years old. Can you access the iSY from your browser?

it is running all the programs (although over the past little while all of the lights have randomly shut off) but I have upwards of 20 programs controlling about 30 insteon switches and they are still running properly every day, I just can't access the ISY to change the programs. 

Even stranger. I tied the Admin Console from an old computer I have in the house and while painfully slow, it worked. Not sure why it did;t work on my main computer. Keeps saying "not found"

I ran into a recent problem on my Mac with the Admin Console. I resolved it by downloading the most recent version of Java (I had a pending update). I deleted the cache and downloaded the Admin Console and my problem with the Admin Console was resolved. Won't hurt to give this a try.