According to the person running the site there are just far too many visitors for the server to be able to cope and the archivist is unable to keep it going.
She is going to leave it up for a couple of days so that people can retrieve their stories, if they don't have them elsewhere, but then it's closing down. So if any NCIS writers do have stories there and haven't got a copy elsewhere, I suggest you toddle over there and retrieve them.
It's a great shame that it's closing down, I know it was a very popular archive with both writers and readers.
There is another NCIS fanfic site - MTAC - I suspect this will get a lot busier.
Cross-posted to ncis_gibbsducky.