Random enemy pattern

I wanna a pattern who move my enemy randomly at all because when i have 3 or 4 enemys they seem like the same enemy movement. this is my code for the random :

            int seed = unchecked(System.DateTime.Now.Ticks.GetHashCode());
         rand = new Random(seed);

And here the code for process the move:

   public  void move(GameTime time, WorldScreen screen)
    {
        timer += (float)time.ElapsedGameTime.TotalMilliseconds;
        if (timer > 2000)
        {
            switch (rand.Next(0, 3))
            {
                case 0:
                    base.direction = Enemy.Direction.down;
                    break;
                case 1:
                    base.direction = Enemy.Direction.right;
                    break;
                case 2:
                    base.direction = Enemy.Direction.left;
                    break;
                case 3:
                    base.direction = Enemy.Direction.up;
                    break;

            }
            timer = 0;
        }
        timer1 += (float)time.ElapsedGameTime.TotalMilliseconds;
        if (timer1 > 50)
        {
            timer1 = 0;
            if (direction == Enemy.Direction.down)
            {
                if (!MoveCollision(new Vector2(position.X, position.Y + speed), screen))
                {
                    base.position.Y += speed;
                    ActualAnimation = getAnimation("rundown");
                }
                else
                {
                    base.direction = Enemy.Direction.right;
                }
            }
            if (direction == Enemy.Direction.up)
            {
                if (!MoveCollision(new Vector2(position.X, position.Y - speed), screen))
                {
                    base.position.Y -= speed;
                    ActualAnimation = getAnimation("runup");
                }
                else
                {
                    base.direction = Enemy.Direction.down;
                }
            }
            if (direction == Enemy.Direction.right)
            {
                if (!MoveCollision(new Vector2(position.X + speed, position.Y), screen))
                {
                    base.position.X += speed;
                    ActualAnimation = getAnimation("runright");
                }
                else
                {
                    base.direction = Enemy.Direction.left;
                }
            }
            if (direction == Enemy.Direction.left)
            {
                if (!MoveCollision(new Vector2(position.X - speed, position.Y), screen))
                {
                    base.position.X -= speed;
                    ActualAnimation = getAnimation("runleft");
                }
                else
                {
                    base.direction = Enemy.Direction.up;
                }

            }
        }
        ActualAnimation.update(time, position);
    }

but this code just do the same pattern for all enemys on the room. thx for help me with it .