Hi Doug,
Thanks a lot for your help. I just read more carefully (and in french !) the MSDN help about autoyield property and it clearly says that it's a good idea to set it to .F. when there's ActiveX control or VFP controls such as Grids (my case !) on the form...
In a column of my grid, I show the result of a function that gets a value of a field in another open table. when I do some treatment on that table, I think that the refresh of the grid, or some other event of the grid that calls the function of the column, move the current record of my table so my code continues without knowing it's not on the same record...
Anyway, after what I said you in the first paragraph of this reply plus the fact that I'm positive that setting the property to .F. resolve my problem, I think I will put it to .F.
thanks anyway !
Best regards