All of a sudden I'm getting this error, and cannot log on using any server.

AUTO [1] Infected with a virus or trojan, please clean your system. Cleaner @ http://www.moosoft.com (P12).

Do I really have a virus or trojan, or is this caused by some cookie or something? I certainly find it suspicious that I'm being directed to a site wanting me to purchase a "cleaner.

Thanks in advance for any help!