Just got hit by conficker. Weird

Interesting problem. I got an email from my ISP saying they detected conficker related traffic from my connection. I'm going WTF. Check my main system-CLEAN. Check secondary system-Clean. Check system in bedroom-CLEAN. A few days later get another email-same checks, same results.
This time I check the computer in the front room-which only runs folding@home and I haven't even been on it in at least 3 months and my last house guest was about 6 months ago. It has the paid for version of Malwarebytes on it.
Full scan with Malwarebytes finds nothing. Go online and check the Conficker Eye Chart-FAIL.
Run the Conficker Removal Tool and it finds 6 infections and removes them, so system is clean now.
Date stamp says I got hit about a month ago only thing I can think of is folding got slammed and passed it on because that computer is set to only allow internet access to folding and block all other traffic.