oh dear. I can see how this happened -- in many cases they may not still have samples to derive new sums from :(

Earlier today, a virus signature from the virus "DOS/STONED" was uploaded into the Bitcoin blockchain, which allows small snippets of text to accompany user transactions with bitcoin.  Since this is only the virus signature and not the virus itself, there apparently is no danger to users in any way.  However, MSE recognizes the signature for the virus and continuously reports it as a threat, and every time it deletes the file, the bitcoin client will simply re-download the missing blockchain.

What a heinous prank! Hilarity ensues (via gwire)

good research coming out of McAfee -- lots of Eastern European, Russian, and ex-USSR-country cybercrime businesses nowadays, apparently