Old viruses continued to infect new computers in March, according to the latest antivirus data from Sophos.

Zafi.B continues to dominate the top 10, accounting for over 45 per cent of infections reported in the month. Older version of Netsky take up six of the top 10 places.

"March's virus chart is dominated by old timers such as Zafi-D and several versions of the Netsky worms. Indeed, only one of the top 10 first appeared in 2005," said Carole Theriault, security consultant at Sophos.

"Poorly protected computers are the only reason these old viruses continue to wreak havoc. Some of these established threats are so widespread, they are preventing more recent viruses from breaking into the top 10."

The data also showed that 2.63 per cent of emails monitored in March were infected with a virus. This is a big drop on February's 3.6 per cent.

Meanwhile the Hotmail Hoax enjoyed its ninth month at the top of Sophos' hoax charts. The email purports to be from Hotmail support staff checking inactive accounts.