Just to make sure i get this right.
Are you trying to spawn a Score5 object every 5-16 secs?
if so you are using the random function wrong. Random(X) is a random value between 0 and X.
So if you want a random value between 5 and 16 you will have to use it like this 5+random(11)
Your timing is also off because you do not restart the layout.
By setting the time scale to 0 you just pause the game. So when you reenter the game you resume from where you died the last time.
Use the System-->restart layout action
On a side note. You are really over complication your project. You could just have 1 game screen and 1 event sheet for the easy, medium and hard.
When you pick the difficulty on the startscreen just set a variable which holds the spawn time you want for that difficulty. and then use that variable in your "spawn enemy every x seconds" action
so instead of:
System-->every 4 seconds --> enemySpawn...
System-->every spawnTime seconds --> enemySpawn...
Where spawnTime is your variable. In easy set to 4, medium set to 2.5 and hard to 1.5
It will cut your layouts and sheets by 2/3 and will make it much easier to maintain.
Let me know if I did not make myself clear <img src="smileys/smiley1.gif" border="0" align="middle" />