Hi Richard:
I’m using FCP 6.0.4. I have an external drive I use for my scratch. It’s the same drive I used on the older system, so maybe it’s bring back into the mix some out-dated information or preference? I just reset Disk Utility permission repair again and it did work to release me from the permissions denied curse– for now, but I bet something in my legacy system is causing the problem, as you seem to have surmised.
dw