There is a virus that is making the rounds on livejournal. Apparently, a troll journal makes a post regarding moving a community to a new link (on YOUR journal); they also link to a page where "old posts" will be archived. If you have this virus, it will post to all of the communities that you are a member of and delete content in all communities. It's a confusing, tricky bugger.
If you happen to come across a post of this nature, DO NOT CLICK ANY OF THE LINKS CONTAINED WITHIN IT!
If you would like to read more about this virus, you can do so at </a></b></a>upstart_crow's blog, found here. Be sure to read it thoroughly, as it gives tips on how to remove the virus, as well as tips on how to avoid it.
We don't want our content deleted, you don't want your content deleted, so keep an eye out!
Thanks scout78 for passing on the information.