Figured it out. The version of the program itself on my internal hard disk was older (2009 rather than 2009.5 I believe).

This is a problem with the Band-in-a-Box Setup program on the UltraPak disk. The older version was on my old laptop, and Migration Assistant moved it to the new laptop. Then when I ran BiaB Setup, it didn't detect that the program itself needed updating. Presumably it just saw that there was a version of the app and skipped installing that.

Many thanks to all who have been puzzling over this with me.