Ok, Thanks Pshaw, if you all are aware of it and can fix it I am good. Very happy to find that you found the little guy (the bug) and will crush it under Stardocks Iron shod boots of programing goodness!
Since so many people have hit this bug and we had a devil of time figuring it out, I thought I'd share some background:
The code was makes sure that you'd used all of the events before recycling them. When the game got to the end of the list of "normal" events it incorrectly was jumping to the precursor events for normal worlds. This is why we couldn't easily reproduce it initially -- I would colonize a dozen or so worlds with one set of map settings and everything seemed fine. I would start another game with different settings and still no repro! The trick was that have to colonize roughly 30 planets in the same game before the game started displaying the precursor colonization events . However, we started to get some reports with the magic number and we're finally able to track it down. The fix was actually pretty easy. The fix happened at the cusp of 1.7 release and didn't make it in.