OK another quick update - I created a new user on my mac pro, and the installer works fine. What the?!?!?
At a guess, something in ~/Library folder is interactiving in a negative fashion. Easy way to test is to rename the (hidden) folder from a different (admin) account and log back in as the problem user. That blows away all kinds of things, but if it works you can try to do a comparison of the new and old ~/Library folders.
And of course you can log out, back in as an admin user, move the old ~/Library folder back into place to restore things.
If you are comfortable digging into things another option would be to browse the ~/Library folder structure for Daz/Carrara things, rename them and try again.
On the whole, I haven’t seen as many user profile issues on OS X as on Windows, but that doesn’t mean they don’t exist (and I’ve dealt with far more Windows than OS X users so nothing should be read into the relative frequency)