I have a course with news forum, labels and one questionnaire. Nothing more.
I try to perform a course backup,
I get the first page (the one starting with "Include All/None" and closing with "Backup role assignments for these roles"), I leave defaults untouched and I push the "Continue" button.
I get the second page (the one starting with "Name:" and finishing with "Include role assignments") and I push the "Continue" button.
WITHOUT ANY EXTRA MESSAGE ON THE SCREEN, waiting a bit, I am asked to download the page "http://myserver/moodle19/backup/backup.php"

I have server->debugging->Debug messages = ALL: Show all reasonable PHP debug messages
By changing the Debug messages to "NONE: Do not show any errors or warnings", all the process is correct and the backup file is build.

I observed the same behaviour on FF3 and safari3.1.

I can provide the course for testing purposes but only privately for privacy reasons.
Is this a course level bug or a questionnaire level bug?
I am using last weekly Moodle and last Questionnaire available from http://download.moodle.org/download.php/plugins19/mod/questionnaire.zip