This warning is taken from ongoingmelody about a really bad virus running around LJ right now.
" A terrible virus has been rapidly spreading itself through LiveJournal communities over the past few days. Basically, seemingly-harmless links are posted by a robot who hacks the maintainer's account. Once the links are clicked on and activated, a worm virus inserts itself into the user's computer. oceandezignz says: "The links in question take you to a Russian language NON-LJ website where you will end up with a keylogger on your computer that tracks your passwords and the like for all the services you use (LJ, email, etc)." Additionally, the maintainer(s) of the community get removed, and the community itself becomes helplessly subject to viruses and spam. "
Please be careful out there guys.