After confessing one of his own mistakes, Crazy4laptops asked the Windows forum about other members' "not so smart moments with computers?"
I thought I'd share two of mine:
1) I once beta-tested a new backup program (this was in the late 1980s when we backed up to floppies) and liked it so much I started using it regularly. I forgot it was not a finished product. A year or so later, I lost everything on my hard drive. Then I discovered that I couldn't recover anything from the backup.
The moral: Don't use beta software as if it was the real thing.
2) In my last months of suffering with dial-up Internet access, I kept losing my connection. I spent hours on the phone with my ISP and my phone company, and no one could identify the problem. I changed modems and that didn't help. I changed OSes and that didn't help, either. Then DSL became available in my neighborhood (hooray!) and I gladly gave up the dial tone. While the techs were installing the DSL, one asked if I had a phone cord to connect the line to the DSL modem. I handed him the one I had been using for dial-up. He took one look at it and rejected it. It was worn out and unreliable.
That's when I learned that, when troubleshooting, you should always check the cheapest, easiest-to-replace link in the chain first.
Read the original forum discussion for other people's confessions.