My first programming related memory is of the QBasic interpreter.

I had written some code I was quite happy with, but not saved it yet. As part of a subroutine for sound output, I quickly wrote a loop from 20 to 20000 to output a test signal over 1 second each with that frequency via the PC speaker and hit execute.

Realizing my mistake, It being MS-DOS and thus single-threaded, I couldn't Ctrl+C out of it without killing QBasic altogether and losing my code. I couldn't turn town the PC speaker.

I ended up closing various doors between the PC and me and waiting it out.