Thanks for the answer Nancy,
Really really appreciate for all your reply (specially something 'bout tapioca :) )

>I'm sorry to say that I'm out of ideas...I hope that someone else here will jump in any time now! :) Good luck with your problem. Let us know how you resolve it.

I've already resolve this problem,
I add a new method call reset

Grid1.reset()
LOCAL lColRemove,lColRemoveName,xRemObj,xRemObjtemp
WITH THIS
.RESETTODEFAULT('RecordSource')
.RESETTODEFAULT('ColumnCount')

FOR xRemObj=1 TO 100

lColRemove='THIS.COLUMNS(xRemObj)'
IF TYPE('&lColRemove.')#'U'

lColRemoveName=&lColRemove..name
.REMOVEOBJECT(lColRemoveName)

ELSE
EXIT

ENDIF

ENDFOR
ENDWITH

And Problems gone for goods (I test it 60 times today)

Regards,