After adding a number of quizzes, student grade data failed to be displayed in the gradebook. Out of three courses - two had this problem, while one worked as expected. The two that failed had about 50 students and 75 quizzes. Prior to adding quizzes all three course display student data as expected.

After reinstalling the latest version of Moodle 1.7.1 - All grades once again displayed student data as expected. Upon reinstalling Gradebook Plus v2, once again student data failed to display in the gradebook.

Moodle is running in a shared Linux server through Siteground.com