This is exactly what i needed to get started! Thanks!

YES! Have finally figured it out. Just had to take the i+1 out of the bracket.

i = i + 1
                TextBox1.Text = (i)

        MaxRows = ds.Tables("CustomerDetails").Rows.Count

        Do Until x = MaxRows

            If txtCustRefNum.Text = ds.Tables("CustomerDetails").Rows(x).Item("CustomerReference") Then
                txtCustRefNum.Text = ("CR" & i + 1)
                x = 0
            ElseIf txtCustRefNum.Text = ds.Tables("CustomerDetails").Rows(x).Item("CustomerReference") = False Then
                x = x + 1
            End If
            
        Loop

This code works for the first two entries in the database, when it gets to the third one it just freezes the whole program. Any idea why this may happen?

        
Dim i As Integer = 1000
Dim x As Integer = 0

        Do Until x = MaxRows

            If txtCustRefNum.Text = ds.Tables("CustomerDetails").Rows(x).Item("CustomerReference") Then
                txtCustRefNum.Text = (i + 1)

            ElseIf txtCustRefNum.Text Is Not ds.Tables("CustomerDetails").Rows(x).Item("CustomerReference") Then
                x = x + 1
            End If
            
        Loop

I have come up with this so far. Does it make any sort of sense or do you want me to explain what i am doing in each part of the code?

That code works a treat! And even better it actually makes sense to me after reading it over a few times! haha! Thanks for the help!!