To follow up on 1st anon:
The boxes contain 2V and V reward. Half the time you open the 2V and half the time the V box.
If you never switch, on average, you get 3V/2 reward
If you always switch, on average, you get ... 3V/2 reward.
You can't have a strategy in this game, unless you have some idea of what range of values constitutes a large and small reward.
The monty hall problem works because the game master has extra information which he is revealing by opening a door. No such extra information is being revealed here.