Heads up: Hackers are starting to hack into people's journals. Some delete all the entries on a journal and post up links to viruses, and some delete entries on a community and post up links to viruses. Obviously, you should not click any of the links.
They seem to mostly target high traffic communities and users, but just in case, it would be wise to tighten up security on your LJ by making sure that your password is difficult to guess, and that you're using a reliable e-mail for your LJ e-mail.
EDIT:
xenoamorist alerted me to this! The hackers use your old e-mails to gain access to your accounts! To stop your old e-mails from being associated with your journal,
go here. Note that if you changed your LJ e-mail address (Like me), you'll have to wait six months before the option is available. =(
Backing up vital entries may also be wise. (Conversely, if the link has nothing you like, you could always manually save the entries and comments by going File → Save As and saving each individual entry that way. Of course, that means you'll have to manual expand any collapsed comments and such, but if nothing works, that will.)
This entry has more information.
If you're wondering what the virus-linked entries look like:
Dear friends, I, as the maintainer of the community, have to inform you that, due to the recent tragic events, I've decided to stop using LJ as a platform for my community. From now on, all new depression-related materials should be posted to the new community I've recently created, as for old posts, you will be able to find them there.
I haven't a clue as to what the ones for a personal journal would look like.
Bots and viruses! What next?