Tattie Bogle, your problem seems different from mine, since you have that loud buzzing. I had a loud buzzing once, and it was caused by a MIDI controller (thing that looks like a piano and puts music into the computer.) I simply replaced the controller. I suppose a loud buzz has to be caused by a component capable of making sound, such as a speaker, microphone, Realtek Audio or a MIDI controller.

I have no doubt that when your computer makes a loud buzzing and then crashes, that its system is overloaded. But that's probably not the cause, it's the result of what's wrong.   

Recently the motor in our hard drive started to go, but it made a thin, continuous, high-pitched squeal.

Moorleyman, I'm willing to bet that your problem and mine were caused by the same update. It's vexing that there are so many self-appointed experts on the Internet giving feeble advice like "Check your sound settings," when the problem wasn't caused by my equipment at all.

After the re-install I had to go to Video Settings and restore "Enhance My Appearance." Bless their hearts.