@ Hopeless Newb and Veers, the OP was talking about that random event where a civilization has discovered some precursor tech which slowly makes them more powerful, there is a similar one where they discover some device called a Tacharik or something (I forget the name) which was used long ago by that demi-god bieng with the Dread lords or something and it has the same kind of effect.
I've never had it happen to me and it really only seems to happen to the weakest or one of the weakest players, although like V1m said, I've seen it happen to a powerful race or one that was already growing powerful. However I've never been the weakest civ for very long, actually I usually come out at the top from the start, so I dunno. Actually, its possibly an AI only event because the player could become too powerful with this event, but I don't know how to confirm that.
@Veers: Maybe Master U meant the Corvettes since a Corvette is a naval ship class. However the Precursor ranger and corvette events have different pictures from the precursor tech random event. However the precursor ship event does happen to you.