I have not seen an analysis as to how to avoid "running as administrator." You can set it up so it always does.
Just as you have done, you can try to give sufficient rights to the various driver/folder locations, but I suspect there is more to it.
Keep in mind that the authorcore is Sonic/roxio, and we really don't know how Adobe has hooked into their code. Also, any burner programs have always had issues with sharing.
Let us know if you find a way.
Thanks! I only author DVD's once a month or so, so I probably will just let it be. I wanted to solve this in case it would cause problems in other CS6 software but it seems like it is limited to Encore - which I never liked much anyway.