I'm not sure what you're asking?

In the meantime I believe I've solved the problem by changing the AfterRowColChange method to this:

LPARAMETERS nColIndex
LOCAL i AS INTEGER, cAlias AS STRING

* I've always felt that the grid control is a bit temperamental and found that setting the controlsource to itself 
* stabilizes it.  

cAlias = ALIAS()    && added now
TRY
   WITH THIS
      SELECT(.RECORDSOURCE)   && added now
      .nActiveRow 			= .ACTIVEROW
      .LastActiveCell[1,1] 	= .ACTIVEROW
      .LastActiveCell[1,2] 	= .ACTIVECOLUMN
      .lLastRow = .ACTIVEROW= RECCOUNT(.RECORDSOURCE)
      FOR i = 1 TO .COLUMNCOUNT
         .COLUMNS(i).CONTROLSOURCE = .COLUMNS(i).CONTROLSOURCE
      ENDFOR
      .REFRESH
   ENDWITH
CATCH TO oEx
   oEx = NULL
ENDTRY

* added next three lines now although I'm not sure they are needed as long as ALIAS() is not empty.
IF cAlias <> ''
   SELECT (cAlias)
ENDIF

I'd appreciate your comments, if any.

TIA

Peter

>>Hi Naomi,
>>
>>Thank's. Maybe your approach is the sounder one, although I can't offhand say why. I'll certainly give it a try.
>>
>>As to the try...catch, my thinking was that, if the replace, for whatever reason, were to cause an error, I don't want the whole app to fail.
>>
>>In the meantime I've narrowed the issue down: the enter on the checkbox for some reason causes the grids columncount to be set to zero. Why, I don't know.
>>
>Do you have a button on your form with Default property set to true?