The first computer I had was an 8088 XT clone with a turbo setting that went from 4.77 MHz to 8 MHz! It was blazing fast!
I remember the very first thing I did when we brought the computer home from the computer store was I went through the hard drive and saw this file that I couldn't possibly use, and deleted it. Why? Who knows, I was a dumb kid.
Yes, you guessed it. COMMAND.COM.
When I rebooted my computer, I got the "COULD NOT LOAD COMMAND.COM" error and I freaked out because I f'ed up my computer on the very first day I had it and my parents would kill me. I knew I could boot from my DOS 3.2.1 diskettes, but not from my hard drive, so after straining, I somehow managed to figure out how to copy the command.com from my diskette onto my hard drive and it worked.
And thus started my illustrious career in debugging computer problems and IT support, which continues to this day.