Hi all, I have an application which have an main form (inherit from TForm) A, another form B (also inherit from TForm) where B contains a dataform C (also inherit from TForm). B will be exist during the program life cycle where C will be created and destroyed when different function is loaded. I have encounter a bug when I open and close from C rapidly without any operation. The error look like "Access violation at address 4BDExxxx in module 'IDAPI32.DLL'. Read of address xxxxxxxx." Is anyone met this error before? How to fix it? Thanks for any help. Mark Leung

Maybe some data connection exist when you destory form c . Why not keep datamodule form alive ? Close the datamodule when the application had close.

scotthsiao, I know what is your meaning, but form C is actually a place holder for different function. It will lead to memory leakage if I keep them all. I just found that the ordering of the construction of form C may help to fix the error (I hope). And the ordering sequence is as follows in 2 versions (Ver.A is older version). Ver A: 1. create form C 2. disable controls 3. get data from DB 4. enable controls 5. merge form C into form B 6. ShowModal B Ver B: 1. create form C 2. merge form C into form B 3. disable controls 4. get data from DB 5. enable controls 6. ShowModal B Dooes anyone know why Ver B help? Mark Leung

Sorry, I can not understand what difference from ver A and B. If you do want to fix the problem, just put a datamodule form individual. Place all the data component in the form. Other forms can use the datamodule to open or close the query or table.