Gradebook

I expect this comes under the category of "user error", but I have an instructor who has called me a couple or three times about "losing grades" out of the gradebook.

We have Moodle 1.5.3+, LAMP server, and installed gradebook plus from Humboldt in January.

• The instructor put grades with the edit grades tab.  Changes were saved.  Later, the instructor put in comments with the assignment interface. Changes were saved.
• At some point, the edit grades pop-up window said "You haven't saved for 10 minutes, do you want to save?"  And the instructor did.
• And then, the next time the instructor went back to the course, the grades were gone.  This has happened at least twice.

It is possible that the instructor in question might have had two windows open, one of edit grades and one of the regular assignment interface.  (The instructor does not think this was true, but can't really remember)  I have been unable to replicate the problem. 

I have some questions for the Humboldt guys!

1) Does the 10 minute save come up on edit grades just because the window is still open?  This could be confusing if the instructor did save the grades, but kept the window open while working on something else.

2) If the edit grades window is open AND the assignment interface window is open, does the last one to save overwrite the data? (I would expect so, but I have had some very strange problems that I attributed to having multiple windows open and being logged in as two different users at the same time.  Bad idea!)

3) Any other ideas?  I have told the instructors not to use both tools at once, but maybe I am missing something!

Thank you for any help!
atw