The BBC has been hit by a virus for the second time in a month.
Subscribers to The Archers mailing list, which provides daily updates on the popular radio soap opera, were sent the SoBig worm by mistake last Thursday.
"Our mailing lists get a lot of traffic and an outside user had it in their address book," explained Jonathon Kingbury, head of editorial affairs at BBCi.
"The virus package came through Webmail from a moderator and was mistaken for a .gif file. We've since had talks with the major internet service providers and the number of infections that made it through are tiny: maybe 10 or so subscribers."
Had the outbreak occurred a month earlier it would have been a lot more serious, but antivirus vendors have updated their virus definitions.
"Viruses are staying in circulation for longer and reinfecting more often," said Raimund Genes, president of European operations for Trend Micro.
"It's the one per cent rule: even if one per cent of computers still have the virus it obviates the other 99."
SoBig affects PCs running Windows 95 onwards. It contains an SMTP engine to mail itself to all addresses on a PC, and can spread through network shares.
The worm is easy to spot, with just four subject headers and attached file names. These are: 'Re: Movies', 'Re: Sample', 'Re: Document' and 'Re: Here is that sample'.
The infected attachments are: 'Document003.pif', 'Sample.pif', 'Untitled1.pif' and 'Movie_0074.pif'.