I have just started to use this module for the first time on my production site. I think it fills an important role not catered for elsewhere.
I was delighted that a student asked me for help through this medium. I answered his request and then closed the dialogue. The setting was was for the closed dialogues to be deleted after "0" days, which the pop-up help file said meant it would never be deleted.
However, when I logged in the next day, the dialogue had disappeared, suggesting that this zero setting doesn't avoid deletion as claimed. In fact, it was deleted within 24 hours!
So of course I will change the setting to 365 days, but that means an archived course that is still online will be changed after that time. I would still like a "never delete" functionality.
Any ideas about this issue? Is it just me or have others experienced this? What is the cause - a bug or something else? Any feedback or suggestions will be gratefully received! 
Tim.