I do not know why this happens. I would however start keeping backup copies of all your work.

>Thanks For Your reply of my 'FormSet Corrupts'.
>I try the first Method , Unluckily, I can't restore my code,
>
>I list all my code to a program (The sec. method U teach me).
>wo.. Over 12 pages coding..
>
>Do u know The cause of this 'accident' ??
>
>I know it is not a good way to use ThisFormSet.(after I join this newsgroup).
>Badly, I finish all my project/development.
>
>How can I prevent this accident ??
>Thanks For your Great Help.
>From Agnes