Thanks all for your replies.
Pyxis, this appears a very likely explanation, though I may seek out the SHA2 hash checksum for safety.
[quote]The reason these false positives occur is due to botnets, so anti virus programs add legitimate programs like the mining software to the virus list, but its good to double check with us to sure.
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I have found that the source code for Cpuminer is also available, which I understand makes the program fully transparent and therefore verifiable by the Feathercoin community.
Of course I’ll let you know if my system inexplicably starts mining by itself!