My Zombie Game

So here's this game I've been working for a while.
I've been having some problems which I really need some help with.

1.This is my biggest problem in this game. Whenever I try to play a sound file I get an error. This started after I accidentally pulled my flash drive from the laptop while alice was running from it.

2.How do I lower the amount of events?

3.How do I get the bullet to stop after it hits a zombie?

4.How can I improve my collision detection?

Those are my main problems for now. Any help with any of them would be great Also I want to know if it's good so rate the game from 1 to 5, with 1 being the worst and 5 being the best. The file link is at the bottom because it exceeds the upload limit (it's +45mb).
Note: you might see some names of song while it's loading, that was because I was bored and wanted to see if I could actually play songs while playing.
http://www.sendspace.com/file/207jaj