Hi Anthony,
No, that why i need to create the custom paper size.
I've tried create a size eg. like A4, and it also will missing after certain unknown timing.
The most weird is, this only happens on one of my office computer, but not others.
Perhaps, this pc had turn on the settings for windows to do a house keeping to remove all user defined paper size after certain unknown timing, that i guess, and i can't find any source to prove it.
If you google, you can found that this problem had existed couples of years since windows 7, not common but still exists day by day for lucky people like me.
Reformat a windows sound like a solution, but i not intended to, at least, not now.
Any clues? Tqvm.