Error when grading filtered assignments

Hi,

Using Moodle Release 2.6+ (Build: 20131205)

I just wondered if anyone else is experiencing this problem:

Choose an assignment which has more than one submission outstanding for grading.

(It doesn't seem to make a difference what type of assignment - tried with pdf marking, & on-line, so assumed would be the same for all).

Select View/Grade all submissions.

Set filter of "Requires Grading"

Click the Grade icon in the grid for the first assignment.

Click Save & Next (the error happens even if you haven't done any grading, so no need to go through the grading process).

Continue to click Save and Next until you reach the last record.

When you click Save & Next while on the last record, the error below is displayed.

You are then returned to your homepage.

Thanks

Rachael