The potenially very valuable script Focus Star contains two errors one in line 25 and one in line 210.

This script _requires_ 2.0b73 or after. Hence the errors with 2.0b72 (which you are running). However, I guess there should be some warning.

Fixed. Attempting to run a script with a minimum version requirement will elicit an alert before running. Also, any such script in the Download SCripts dialog will be marked in red.