Hello everybody i wrote a code in asp.net that read data from files and draw a graph. It worked but after awhile when i run the program, this exception arise "An unhandled exception of type 'System.StackOverflowException' occurred in mscorlib.dll" in this statement in the code:

if (File.Exists(fName)) <----(here is the exception)
{
    stream = File.Open(fName, FileMode.Open);
    g_day = Deserialize(stream);
    stream.Close();
    int cn = 0;
    if (g_day.Values.Count != 0)
        cn = g_day.Values[g_day.Values.Count - 1].Value;
    Label1.Text = cn.ToString();
}

can u help me