My bad, I replied before thinking! An INSERT INTO works only if you specify a higher value than the current seed. If you use MyISAM then you should take advantage of the -A option of myisamchk:
Quote:
-A or –set-auto-increment[=value]
Force AUTO_INCREMENT to start at this or higher value. If no value is given, then sets the next AUTO_INCREMENT value to the highest used value for the auto key + 1.