Why don't you want to add a ReadOnly column to your table.  Here's an
example that I tested and works:

In your Database:
-----------------
- I have a table tblNames with ID, FirstName and LastName
- Add a ReadOnly column of type Bit (assuming you're using SQL Server)
- Update all rows that you want flagged as "ReadOnly"

You should get the results (for example):

ID   FirstName   LastName    ReadOnly
---- ----------- ----------- --------
1    Joe         Shmoe       0
2    John        Doe         1
3    Jane        Doe         1
4    Homer       Simpson     0

In your program:
----------------
- Add a DataGrid
- Add your table styles
- Add the following code:

Imports System.Data.SqlClient

Public Class Form1
   Inherits System.Windows.Forms.Form

   Private strCnn As String = "integrated security=SSPI;data source=" +
{Place your data source here} + ";persist security info=False;initial
catalog=" + {Place your database here}"
   Dim sqlCn As SqlConnection = New SqlConnection(strCnn)
   Dim da As SqlDataAdapter = New SqlDataAdapter("SELECT * FROM tblNames",
sqlCn)
   Dim ds As New DataSet

   Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load

       sqlCn.Open()
       da.Fill(ds, "Names")
       sqlCn.Close()
       DataGrid1.DataSource = ds

   End Sub

   Private Sub DataGrid1_CurrentCellChanged(ByVal sender As Object, ByVal
e As System.EventArgs) Handles DataGrid1.CurrentCellChanged
       DataGrid1.ReadOnly = ds.Tables(0).Rows
(DataGrid1.CurrentCell.RowNumber).Item("ReadOnly") = True
   End Sub
End Class

** In the code, when the CurrentCellChange event is triggered, I am
checking the ReadOnly column of the dataset.  If it is true, then I make
the ENTIRE GRID read-only.  When I change to a row where ReadOnly is false,
I set the grid's ReadOnly property to false.

It's quick and it's simple !

Cheers !

E