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.
It appears to be a joke or prank, simply because this particular virus does nothing more than periodically show "YOUR COMPUTER HAS BEEN STONED" on one out of every eight computer boot-ups, and is over 25 years old.
I'd like to get a verification here that a) what MSE is actually detecting is the signature for a virus and not actually the virus itself, b) that there is truly no danger to users of bitcoin simply because of the limitations of the blockchain to carry all the code needed for a virus, and c) MSE can and should be updated as soon as possible to bypass signatures found in the blockchain, as its constant alerts of finding threats in the blockchain is not only worrisome, but can create panic and negative perception of bitcoin as a whole, damaging its reputation and annoying users. It's important that MSE be updated with a more selective virus detection algorithm for blockchain files.