>Some details about your operating system and delphi/bcb versions may
>help. It probably wont help much but you never know.

D6 Enterprise (build 6.163) and WinNT 4.0 (build 1381: SP 6).

>It happened with checkboxes and grid, as soon as I check/uncheck it
>and change row, or when I commit.

Well, it may be the same problem, but my checkboxes are not in a grid.
Moreover, it only occurs with check boxes I have recently added to my form
- the ones who have been there for months have no problem.

>I tried to isolate the problem, but nothing.

Once I discovered that having a monitor active removed the problem, I knew
it was beyond my capabilities to solve or isolate this one.

>I tried to make a minimal demo app, but I can't reduce complexity and
>keep the problem alive.

I haven't even tried. But the good news is that my app really is close to
minimal (it was just developed for two people to register some data for
research on prostate cancer). I guess I can remove some forms not
associated with the problem as well as some validation code and put some
fake data into some of my seven tables and send the result together with a
three line description of how to provoke the error to Jason or Geoff. I'll
see what I can do,

Set