ON SHUTDOWN QUIT
CLOSE DATABASES ALL

SET CONFIRM ON                      && <====== ADD THIS
SET TALK OFF
SET SAFETY OFF
SET EXACT ON
SET DELETED ON

CREATE TABLE test ( test N(1) )
FOR i=1 TO 50
INSERT INTO test VALUES (1)
ENDF
SET FILTER TO test=1
GO BOTTOM
SKIP -1

SET MULTILOCK ON
CURSORSETPROP( 'Buffering', 5, 'test')
obrowse1=NEWOBJECT("browse1")
obrowse1.SHOW
KEYBOARD '2'
READ EVENTS

DEFINE CLASS browse1 AS FORM
ADD OBJECT gridbase1 AS GRID

PROCEDURE INIT
* At least 3 rows must be visible
THIS.gridbase1.DOSCROLL(0)
THIS.gridbase1.DOSCROLL(0)
ENDPROC

PROCEDURE gridbase1.BEFOREROWCOLCHANGE(nColIndex)
TABLEUPDATE(2, .T., 'TEST' )
ENDPROC

ENDDEFINE

Explain this is very complex,
but it is correlate with the fact ( a design bug )
that normally the cell textBox Valid event fire after BeforRowColChange,
and that when you use a TABLEUPDATE/TABLEREVERT/ROLLBACK/END TRAN command
with the focus on the grid, the VFP grid C++ code go into a panic sequence.

SET CONFIRM ON it don not remove these problems, but remove the error message.