class Program
    {
        static void Main(string[] args)
        {
            Form1 f = new Form1();

            f.comboBox1.Items.Add(new object[] {"Item1", "Item2"});

            XmlSerializer XmlSerial = new XmlSerializer(f.comboBox1.Items.GetType());

            XmlSerial.Serialize(Console.Out,

public partial class Form2 : Form
{
    Form1 form1 = new Form1();

    ...

    private void button1_Click(object sender, EventArgs e)
    {
        form1.comboBox1.Items.Add(this.comboBox1.SelectedItem.ToString());

FileInfo MyFile;
SqlConnectionStringBuilder ConStrBuilder = new SqlConnectionStringBuilder();
static SqlConnection Con = new SqlConnection();
SqlCommand Cmd;
SqlDataReader DataReader;

...

private void OK_Click(object sender, EventArgs e)
    {
        RegFile = new FileInfo("Sol1.Data." + MyCombo.SelectedItem.ToString() + ".mdb");

        for (int i = 0; i < 23; i++)
        {
            if (RegFile.Exists