iTunes 7.3.1: Unable to address LARGE library? Why?

Just updated to 7.3.1, and subsequently did something I haven't done in a while. Deleted my iTunes Library and started anew. So, in my new blank iTunes window I simply opted to "add new folder" to my iTunes library. For whatever reason, iTunes could only grab the first 700 or so songs from one directory. I have a big "MP3" directory (about 150GB)laying on an external HDD with about a dozen nested subdirectories (named by genre.) Anyone have this issue?

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