@cyberhypnotic:
I can confirm that there sometimes is a problem with 8-player-tournaments, but I am not sure how to reproduce it. This now is on the "Bug-List" and I will look for a fix.
The sorting is another thing I'd like to change, and as there are many planned improvements for the Tournament-System I guess this will come along with that.
@Reece B:
Create the Tournament in AdminCP instead of ModCP and the Error won't show up

Will fix the ModCP in v2.5.5+