[Yoda]

Well, if 75% of all people had a problem then the odds of 5 people (picked randomly) having no problems is .25^5 = 0.0009765 so about 1 in a 1000. Of course, I can't confirm that the five people cited above didn't have problems.

Note: I'm not defending Firaxis, I've never played Civ IV and don't plan to, my brief experience with III was quite enough.