[John]

That's weird. Run this:

CREATE TABLE arcade_challenges (
challengeid int(10) unsigned NOT NULL auto_increment,
fromuserid int(10) unsigned NOT NULL default '0',
touserid int(10) unsigned NOT NULL default '0',
winnerid int(10) unsigned NOT NULL default '0',
loserid int(10) unsigned NOT NULL default '0',
gameid int(10) unsigned NOT NULL default '0',
datestamp int(10) unsigned NOT NULL default '0',
fromsessionid int(10) unsigned NOT NULL default '0',
tosessionid int(10) unsigned NOT NULL default '0',
fromscore float(15,3) unsigned NOT NULL default '0.000',
toscore float(15,3) unsigned NOT NULL default '0.000',
status tinyint(1) unsigned NOT NULL default '0',
PRIMARY KEY (challengeid)
)

It should have done that as part of the product upgrade, though. :/