Thousands of PCs around the world have been paralysed by a security
update that wrongly labelled part of Windows as a virus.

The update was sent out by security firm McAfee and made affected PCs
endlessly restart.

Corporate customers of McAfee seemed to be hardest hit but some
individuals reported problems too.

McAfee apologised for the mistake and released a fix to ensure PCs
started working again.

Ref: http://news.bbc.co.uk/1/hi/technology/8636985.stm