View source for Error/moodle/activity task coursemodule not found

I tried to backup a course in Moodle 2.0 and encountered this message. Does anyone meet this before?
Yes! I've just installed M2.0. RC1 & RC2 both preformed the backup successfully but not so with R-M2.0

Maybe you have this error: http://tracker.moodle.org/browse/MDL-25432

This error is most commonly caused when an attempted delete of a course module fails.

You can look in the mdl_course_modules table for any row that has instance=0 for the course you are experience the error.  If found you will need to remove the mdl_course_modules.id from the mdl_course_sections.sequence specified by the mdl_course_modules.sectionid.  Once removed from the id is removed from the mdl_course_sections.sequence, you can delete the offending row(s) in the mdl_course_modules table.

You should now be able to run a course backup.