It appears that there is a particularly nasty Malware virus hitting various social networking sites - including Live Journal.
It targets communities and generates a moderator-ish looking post that informs members that the community is being closed and it also deletes the communities entries. It also, and this is the extremely nasty it, includes some links that if clicked will infect the person who clicked them with compromise their personal information and their f-list.
If you see such a post on any comm to which you belong do NOT click on any of the links. Instead report the post to LJSupport by clicking on the 'flag' link. I would suggest not waiting for the comm mod to do this, as they might not be around if a post appears.
This is a LJ wide thing, so please keep this warning in mind if you see posts on other communities.
Full information about the virus.
Here is a post by upstart_crow who knows more about this than I do.
Apologies in advance to anyone who is on more than one of my communities - I will be cross-posting this to my other communities.
aingeal8c I have posted to ds_closet and have emailed you. I thought it better to be safe than wait until you are back on-line.