You should be happy that they your website approved one time before they took it away. They never accept my websites. :-(
Issue with editor, just resumbit and check terms and conditions to make sure you have the right section, right title, description etc. dmoz can be difficult at times with editors to get indexed.
DMOZ is a joke, have you really looked. You need a site thats like 5 years old to be listed. MINIMUM They love there power and hold on tp it dearly. I can wait for the day google simply stops pulling data off that. Its like the rich guys son. He is only even wanted around because his DAD has money Same with dmoz, its a crappy old directory, they should be kisssing google's butt up and down the street. Which is another story. Me? I use yahoo for GP.
Selling/buying sites is a sure way to get removed, as they feel the buyer actually cares enough about the listed site/listing, that such a listed site is bought FOR the listing. Gods forbid you want a site for the content. My server went down for 15 minutes and I got my site removed. It's been put back, but heh, DMOZ was down for 6 months and they got to keep their listing An editor could be your competitor ~ While that can not be an "official" reason, I'm sure that it happens. Change of content can also play a HUGE role in it. If you have changed the site, then an editor may have sent it to the queue in another area. The list likely goes on...