You guys are great! Wabe, as soon as I read your post, I realized that I had had some trouble with transferring my login, so I followed grichter's advice to check it with the utility (I used the installer utility); sure enough, when I reset my admin password, everything started working.

I'm grateful, but a little embarrassed, as I used to provide Mac support in-house at a publisher, and should have been able to figure this out on my own...