En todo caso cambia esto
Código vb:
Ver originalDim total as Integer
Dim row as DataGridViewRow
DataGridView1.Rows.Add(1)
total = DataGridView1.Rows.Count
row = DataGridView1.Rows(total-1)
row.Cells(0).Value = txtcantidadd.Text
row.Cells(1).Value = cboproducto.Text
row.Cells(1).Tag = cboproducto.Value
row.Cells(2).Value = cboproveedor.Text
row.Cells(2).Tag = cboproveedor.Value
row.Cells(3).Value = cboserial.Text
row.Cells(3).Tag= cboserial.Value
row.Cells(4).Value = txtcaracteristicas.Text
por esto
Código vb:
Ver originalDim row as DataGridViewRow
DataGridView1.Rows.Add(1)
total = DataGridView1.Rows.Count-1
DataGridView1.Rows(total).Cells(0).Value = txtcantidadd.Text
DataGridView1.Rows(total).Cells(1).Value = cboproducto.Text
DataGridView1.Rows(total).Cells(1).Tag = cboproducto.Value
DataGridView1.Rows(total).Cells(2).Value = cboproveedor.Text
DataGridView1.Rows(total).Cells(2).Tag = cboproveedor.Value
DataGridView1.Rows(total).Cells(3).Value = cboserial.Text
DataGridView1.Rows(total).Cells(3).Tag= cboserial.Value
DataGridView1.Rows(total).Cells(4).Value = txtcaracteristicas.Text