Adding rows to a DataGridView control causes crash but only on second attempt - vb.net

Question

I have a DataGridView (dgvNew) which is populated by a JSON file which is located by a FileSystemWatcher, data is added row by row after being read. It works fine on first file. But if i trigger a new file by copying and pasting the same JSON file it adds the rows again row by row as id expect, but then the whole form crashes with no error.
I've tried TRY..CATCH with WHILE loops for opened the files which works in terms of openning them and adding rows, i just don't understand why it crashes. The code continues to step through regardless even though the form is frozen ? is it Thread related ?
Public Sub subParseJSONs(strFilePath As String, strDesiredField As String)
Dim json As String
Dim strMachine As String
Dim read As New Newtonsoft.Json.Linq.JObject
Dim booErrorJSNOArrRead As Boolean
Dim i As Integer
Dim dgvIndex As Integer
Dim booOpened As Boolean
Dim k As Integer, j As Integer
booOpened = False
k = 1
j = 1
json = Nothing
While json Is Nothing
Try
j = j + 1
If j = 10 Then
MessageBox.Show("J integer reached 10")
Exit While
Exit Try
End If
json = Replace(Replace(System.IO.File.ReadAllText(strFilePath), vbLf, ""), vbTab, "")
read = Newtonsoft.Json.Linq.JObject.Parse(json)
Catch ex As IOException
'MessageBox.Show(ex.Message)
Threading.Thread.Sleep(300)
'GoTo EndOfSUb
Catch ex As Exception
'MessageBox.Show(ex.Message)
Threading.Thread.Sleep(300)
'GoTo EndOfSUb
Finally
booOpened = True
End Try
End While
booErrorJSNOArrRead = False
i = 0
dgvNew.ColumnCount = 6
dgvNew.Columns(0).Name = "TempID"
dgvNew.Columns(1).Name = "DriverName"
dgvNew.Columns(2).Name = "Seat"
dgvNew.Columns(3).Name = "RaceTime"
dgvNew.Columns(4).Name = "ResultTime"
dgvNew.Columns(5).Name = "CarDriven"
dgvNew.RefreshEdit()
dgvNew.Refresh()
Do Until i = read.Item("Result").Count
If Not read.Item("Result")(i)("DriverName") = "" Then
Dim milliseconds As Double = Convert.ToDouble(read.Item("Result")(i)("TotalTime"))
Dim ts As TimeSpan = TimeSpan.FromMilliseconds(milliseconds)
Dim strMMSSmmm As String = ts.Minutes.ToString & ":" & ts.Seconds.ToString & "." & ts.Milliseconds.ToString
Dim row As String() = New String() {i + 1,
read.Item("Result")(i)("DriverName"),
read.Item("Result")(i)("DriverName"),
strMMSSmmm,
DateTime.Now, read.Item("Result")(i)("CarModel")}
dgvNew.Rows.Add(row)
End If
i = i + 1
Loop
read = Nothing
End Sub
I'm expecting new rows to be added to the bottom of dgvNew, which they are, but then it crashes ?