So what will be this Preventable Event?

[The Guard]

I didn't mind the concept, but the execution as others have said was terrible. The scene comes off comedic when it really shouldn't have. The scenewas just stupid, much like the movie overall.

"Terrible" is just...terrible hyperbole.

The Danger Room sequence in X3 was obviously MEANT to come across a little lighthearted, with a couple other emotions within it. Because Wolverine wasn't taking it seriously.

I don't think I've ever read a team Danger Room sequence that didn't feature some comedic elements. Seriously. The only time I've seen The Danger Room taken entirely seriously is when Cyclops is pushing himself, and when it became "Danger".

Stupid? Eh. To each his own, I guess. The effects were fantastic, the atmosphere was great. It wasn't meant to be a great, dramatic scene, just one to introduce us to where the X-Men were after the events of X2. And it worked pretty well.