I explain the why here: [url]why random(a)+b does not working for timers?]
I talk about the problem with the evaluation of Random() every frame, now in the linked topic we are talking about a global timer and fix it with a global variable, you have instance timers so you’ll need an instance variable.
Ok, I see that you already use an object variable for the random value, it’s the best per-instance approach 
, now I would suggest this change, so you don’t need a sub-event per random option:
[code]Conditions: Always (no conditions)
Actions: Do + TimeDelta() to the variable “firerate” of enemy
For each enemy:
Conditions: Variable “firerate” of enemy is >= enemy.Variable(randomfire)
Actions: Create bullet, move bullet, etc.
Do = 0 to the variable “firerate” of enemy
Do = Random(2) + 1 to the variable “randomfire” of enemy[/code]
Check the scene options (right click on the scene, and “Edit the properties”), there is a checkbox with the option “Stop all sounds and musics at startup”, and it seems it’s enabled (stop sounds) by default, disable it in every scene you want to keep the previous music. I hope it works, because there have been some problems concerning this in the past 