ya dude, anyone tecky enough knows due to how the blockchain works a virus wouldn't work, not to mention i think the checksum mis-match would crush any chance of a bug getting into core ;p
ill ask one question tht will prob tell you the culprit
have you installed any of the random alt-coin wallets launched almost everyday?
cause thats where your bug came from guaranteed haha
go from vm do external scan, and for gods sake use a reputable AV atleast like ESET or something
someone above said use Microsoft security essentials, worse answer ever
when i wore a few different color hats back in university we TESTED malicious code around Microsoft security essentials, its total garbage lmao