The universal constant of software development: fixing one bug creates fifteen more. It's like trying to squash a spider only to discover it was pregnant with demon spawn.
You start with 2 errors, feeling smug as you crack your knuckles and fix that "simple issue." Then suddenly—BOOM—17 errors and your computer's practically on fire.
Newton's lesser-known law: bugs can neither be created nor destroyed, only transformed into more complex bugs. Eight years of experience has taught me that confidence while fixing bugs is directly proportional to the catastrophe that follows.