A simple C# generic singleton class

using System;
using System.Reflection;

namespace MiniCafe.Util
{
    /**//// <summary>
    /// this is the base class for singleton mode in csharp. Derived class must have a
    /// privae or protected constructor without any parameters, otherwise exception will
    /// be throwed.
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public class Singleton<T>
        where T : class
    {
        private static T instance;
        /**//// <summary>
        /// instace property of class T
        /// </summary>
        public static T Instance
        {
            get
            {
                if (instance == null)
                {
                    lock (typeof(T))
                    {
                        if (instance == null)
                        {
                            ConstructorInfo constructor = typeof(T).GetConstructor(BindingFlags.Instance | BindingFlags.NonPublic, null, new Type[0], new ParameterModifier[0]);
                            if (constructor == null)
                                throw new Exception("The object that you want to singleton doesnt have a private/protected constructor so the property cannot be enforced.");

                            try
                            {
                                instance = constructor.Invoke(new object[0]) as T;
                            }
                            catch (Exception e)
                            {
                                throw new Exception("The Singleton couldnt be constructed, check if the type T has a default constructor", e);
                            }
                        }
                    }
                }
                return instance;
            }
        }
    }
}