game that was on computer when bought

Hi. I have a game called Rocky Mountain Trophy Hunter that was already installed on my computer and my kids love to play it. But all the sudden now it won't load. Here's what it comes up with:
It seems to be loading , you hear a gunshot but then you hear a funny beep, then a window comes up that says ERROR: Sound initialization failed. You have to click OK. Then another window comes up that says:
Program ERROR rmth.exe has generated errors and will be closed by Windows. You need to restart the program. An error log is being created.
Then you have to click OK again.
Then that's it. I'd like to know what is going on with it. Someone please help.