Binary Reader Help

Hi, I am making a Binary Reader find then read a string and input it into a textbox. I have 2 questions. I need to search for a string and read the string a byte afterwards. The string I am reading can be 1 - 4 bytes long. It is offset between "". (Two quotes [it is inside])

1) Is there a way I can make it find a string faster because right now on large files it just locks up.

2) What is wrong with this code, I keep catching these errors.

        private void button2_Click(object sender, EventArgs e)
        {
            OpenFileDialog ofd = new OpenFileDialog();
            ofd.Filter = "All Files|*.*";
            ofd.Title = "Open Profile";
            ofd.FileName = "";

            if (ofd.ShowDialog() == DialogResult.OK)
                fileLocation = ofd.FileName;

            //Searches for the clan tag
            string search = "clanName ";

            BinaryReader br = new BinaryReader(new FileStream(fileLocation, FileMode.Open, FileAccess.Read));

            // Starting offset
            br.BaseStream.Position = 0x14000;

            string found = "";

            try
            {
                // read next 65536 chars
                found = new string(br.ReadChars(0x10000));
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }

            // Find our starting position in buffer
            int index = found.IndexOf(search);

            textBox1.Text = found.Substring(index, 20);
       
        }