What I learned in the aftermath of my Rainbow-Cursor-From-Hell experience with my iMac.

1. When we solve these catastrophes with our computers we never end up knowing what the problem was. Just that resetting something or starting over from some level worked around the problem.
2. I knew that if I absolutely couldn't fix the problem I could always buy a new computer. Or use the laptop in the other room. So this is nothing like the old days, when a failing computer meant I was off the air until it got fixed. Most of our computers back then were one-off in some way. The parts were not quickly replaced, and there was no overnight shipping from Amazon or an Apple Store down the street. I was lucky, being in Silicon Valley, that there were options there, but it involved a drive, and often a wait of a few days. 
3. In the Rainbow-Cursor case, it was pretty clear after fixing the problem that the internal drive was slowly breaking. More and more disk accesses were failing, so while things would eventually happen, it just got slower and slower. 
4. We can make self-driving cars, but somehow we can't have a failing disk drive send us an email saying "Your computer is about to fail for this reason, we just saved you three days of frustration. Thanks for choosing Apple."
5. In 2001, the evil computer Hal was able to tell Dave exactly when certain parts would fail, although in some cases he was lying. I guess we should be thankful our computers today don't have strong feelings about us personally. 

We should settle down and put some of our effort into finishing the development of technology so many of us depend on for our work and creativity.