>Anyway... I'm sceptical...I figure the origin is relaigiousin some way..maybe an old pagan holiday deemed evil by a conquering culture.<

It was on on Friday October 13, 1307 King Philip IV of France in colusion with the Pope chose for the mass arrests of the Knights Templar.

www.bbc.co.uk/dna/h2g2/A272558

"Upon the conclusion of the West's attempted conquest of the Holy Land for Christendom, the Templars still earned great revenues from their lands, minus the cost to arm knights for crusades. They were exceedingly wealthy and had more funds than any European monarch. France was in great debt to the Templar organisation, and its king, Philip le Bel grew increasingly jealous of the wealth of the Knights. In 1307, upon the death of the then Pope, he brought many charges against the knights, including heresy. It is for this day Friday 13th was come to be known as unlucky, for that was the day that Philip arrested, simultaneously, all the Templars in France in a carefully planned operation. The Templars were alerted, and their fleet (which was greater than that of any nation) departed from France with all their wealth stowed on board, and was never again to be seen in Europe."

Oh...my...dog....it's the 14th....you must be psychic Bloke? Or is it just secret knowledge passed down from the Knights of the Templar that allows you to see forward in time so clearly? ;-)