I'll be surprised if any of know what I'm talking about, but in the Freelancer clone "DarkStar One", there's this one mission affectionately known as Flak Mission 2.
O M F G - it's teh no. 1 pure ass WTF gaming moment of all time.
It's so disproportionately hard, that anyone short of phenomenon hand-eye dexterity will not be able complete it. The stupid thing is that it's one of those crappy turret levels ala KotOR which they thrust upon you, and the gaming is COMPLETELY different from what you would've experienced until then (with the exception of Flak Mission 1 which was easy).
Fortunately, I managed to complete it after much frustration at around the 12-15th attempt after watching a video of it being done.
It's actually so bad, that the developers opened up a thread at their forum where users would send in their SAVE GAME, so the developers would "beat it" and then send it back after that level.
I bet that thread probably still exits.