Selecting an image from a gridview

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C#

.NET

Hello,
I have a grid view which displays images opened from a folder. Once i click on an image from the gridview it shows in my picturebox to enlarge. But when i click on a different image in the gridview it throughs an error stating that i have a negative number and needs to be corrected. Here is the code i have once an image is selected in the gridview:

private void dataViewImages_CellContentClick(object sender, DataGridViewCellEventArgs e)
{           
      string pic = dataViewImages.SelectedCells[e.RowIndex].ToString();
      pic = this._files[e.RowIndex];
      this.Text = pic;
      MessageBox.Show(pic);
      pictureBox.Image = Image.FromFile(pic);
      tsbSave.Enabled = true;
      tsbRotate.Enabled = true;
      tsbCCRotate.Enabled = true;
      saveToolStripMenuItem1.Enabled = true;
      saveToolStripMenuItem.Enabled = true;
}