I've been listed in dmoz for over 4 years with an accurate, unspamy description.
Just checked it recently and the description for my site has been changed, its shorter and someone has cut out a number of relevant words, even mispelling my main keyword. Looks like sabotage and it seems to have worked, the site was number 2 or 3 in its section and now its dropped down.
The order of listing in Dmoz categories is alphabetical by title. So the only way you could have dropped down is if the title has been changed. The order in Google's copy of Dmoz is by PageRank by default (with an option to change to alphabetical order.)
The best place to ask for a *specific* answer is the ODP Public Forum.
But.. if your description was written back in 2000 there's a good chance that it doesn't meet current editorial guidelines. Descriptions tend to be more terse, with a maximum of two sentences and perhaps a dozen words or so, with no hype or promotional wording.. something that tends to be in "older" descriptions quite often.
If the description isn't accurate or mis-spelled, then you can use the "Update URL" request. Updates tend to be dealt with quite quickly.