Use care online, update your anti-virus and spam-ware regularly.
Do not visit stupid websites that load these viruses. ~~~~
Technology Reporter, BBC News, Silicon Valley
Page last updated at 09:03 GMT, Wednesday, 6 May 2009 10:03 UK
Twelve million computers have been hijacked by cyber-criminals and detected by security vendor McAfree since January, the firm has said.
It reports there has been a 50% increase in the number of detected so-called "zombie" computers since 2008.
The true number of newly-hijacked PCs is likely to be higher than those detected by McAfee alone.
The figures come as a report from Deloitte said a global approach to cyber-security is needed.
"Doing nothing is not an option," said Deloitte's Greg Pellegrino.