Forums Connection Issues Unable to login due to "trojan or virus" issue

I just started getting the following message when I tried to log into IRC using MIRC:
AUTO [1] (174.48.59.171) Infected with a virus or trojan, please clean your system. (P422).

I have run both Norton AV and AVG Antivirus and both programs tell me my system is clean. What do I do now?
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