Operation did not succeed because the program cannot commit or quit a cell value change

Question

I know it could be asked several times over SO but i still need your help. My grid is on some another form where its events are written. In an another form i have the following code which from whcih i am accssing the grid via forms object and exception is coming. I got the following error message :

"Operation did not succeed because the program cannot commit or quit a cell value change."

If objUBFormFieldsTable.TotalPagesInMultiPageClaim - 1 = objUBFormFieldsTable.CurrentSelectedPageNo Then

                            objfrmVerifyClaimUB04.dgvLineItem.Rows.Clear()
                            objUBFormFieldsTable.objstruUBLineItems = Nothing
                            If objfrmVerifyClaimUB04.ValidateLineItemsTotal() = True Then
                                If MessageBox.Show("Mark IMAGE ID - " & Convert.ToString(intCuurentlySelectedImageId) & " as attachment?", "Mark as attachment[Y/N]?", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button1) = Windows.Forms.DialogResult.Yes Then
                                    StartWait("Please wait, while submitting current image as ATTACHMENT")

                                    objClaimsInfo.MarkImageAsAttachmentMV(intCuurentlySelectedImageId, gstruCurrentLoggedInUser.intUserID, strImageSubType)
                                    lvwImageList.Items(lvwImageList.SelectedItems(0).Index).ImageIndex = 4
                                    blnLineItemsReadedUB = False
                                    objUBFormFieldsTable = New clsUBFormFieldsTable

                                    loadNextImage()
                                End If
                            End If

i have followign events for grid

Private Sub dgvLineItem_CellBeginEdit(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellCancelEventArgs) Handles dgvLineItem.CellBeginEdit
    Try
        With dgvLineItem.CurrentCell.Style
            .BackColor = Color.Yellow
            .ForeColor = Color.DarkBlue
            .Font = New Font(dgvLineItem.DefaultCellStyle.Font, FontStyle.Bold)
        End With
    Catch ex As Exception
        'MsgBox(ex.Message) 
        Throw ex
    End Try


End Sub

Private Sub dgvLineItem_CellEndEdit(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles dgvLineItem.CellEndEdit
    'Dim strCurrentFieldValue As String
    Try
        With dgvLineItem.Item(e.ColumnIndex, e.RowIndex).Style
            .BackColor = Color.White
            .ForeColor = Color.Black
            .Font = New Font(dgvLineItem.DefaultCellStyle.Font, FontStyle.Regular)
            '.Font = New Font("Arial", 9, FontStyle.Regular)
        End With

    Catch ex As Exception
        'MsgBox(ex.Message) 
        Throw ex
    End Try


End Sub

Private Sub dgvLineItem_CellEnter(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles dgvLineItem.CellEnter
    Try
        ShowAnnotationForLineItemCell(e.RowIndex, e.ColumnIndex)

        dgvLineItem.BeginEdit(False)
        'CType(dgvLineItem.CurrentCell, DataGridViewTextBoxEditingControl).TextBox.SelectionLength() = 0
        If dgvLineItem.CurrentCell.IsInEditMode AndAlso TypeOf dgvLineItem.EditingControl Is  _
        DataGridViewTextBoxEditingControl AndAlso Convert.ToString(dgvLineItem.CurrentCell.Value) <> "" Then
            SendKeys.Send("{HOME}")
        End If

        Dim hFocus As Long
        Dim hCaret As Long
        'Dim pic As Long

        hFocus = CLng(GetFocus())
        hCaret = CLng(CreateCaret(dgvLineItem.EditingControl.Handle, IntPtr.Zero, 8, dgvLineItem.CurrentRow.Height))
        ShowCaret(dgvLineItem.EditingControl.Handle)
    Catch ex As Exception
        'MsgBox(ex.Message) 
        Throw ex
    End Try

End Sub
   Private Sub dgvLineItem_CellValidating(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellValidatingEventArgs) Handles dgvLineItem.CellValidating
    Try
        Dim strSpecialChars() As Char

        If blnIsClaimLoaded = True Then
            dgvLineItem.EndEdit()
            With Convert.ToString(dgvLineItem.CurrentCell.Value)

                strSpecialChars = New Char() {"`"c, "~"c, "!"c, "@"c, "#"c, "$"c, "%"c, "^"c, "*"c, "("c, ")"c, "-"c, "_"c, "+"c, "="c, "{"c, "}"c, "["c, "]"c, "|"c, "\"c, ":"c, ";"c, "'"c, "<"c, ">"c, "."c, "?"c}

                If .IndexOfAny(strSpecialChars) <> -1 Then
                    e.Cancel = True
                End If

                Select Case e.ColumnIndex
                    Case 0      'REV CODE
                        If .Length <> 3 Then
                            e.Cancel = True
                        End If

                    Case 1      'CPT
                        If .Length = 0 Then
                            Exit Sub
                        End If
                        If .Length < 5 Or .Length > 11 Or .Length = 6 Or .Length = 8 Or .Length = 10 Then
                            e.Cancel = True
                        End If
                    Case 2      'NDC
                        If .Length = 11 Or .Length = 0 Then
                            Exit Sub
                        End If
                        If .Length <> 8 Then
                            e.Cancel = True
                        End If
                    Case 3      'SERV DATE
                        If .Length = 0 Then
                            Exit Sub
                        End If
                        If .Length <> 8 Or CheckIfValidAndNotFutureDate(.ToString) = False Then
                            e.Cancel = True
                        End If
                    Case 4      'SERV UNIT
                        If .Length = 0 Then
                            Exit Sub
                        End If
                        If .Length > 5 Then
                            e.Cancel = True
                        End If
                    Case 5      'TOTALCHARGES
                        If Not IsNumeric(Convert.ToString(dgvLineItem.CurrentCell.Value)) Or Convert.ToString(dgvLineItem.CurrentCell.Value).Contains(".") Then
                            e.Cancel = True
                        Else
                            Exit Sub
                        End If
                End Select
            End With
        End If



    Catch ex As Exception
        MsgBox("Error in dgvLineItem_CellValidating " & ex.Message)
    End Try
End Sub

i am unable to find out the actual bug, help me....