Viruses wreaked havoc on at least 1 million personal computers during the weeklong National Day holiday, according to Jiangmin Co, a leading Chinese antivirus company.
The company's monitoring system detected that more than 118,000 computers crashed on October 6 alone.
"Viruses have been extremely active during the long vacation because more people chose to stay at home and surf the Internet, shopping online or playing online games," He Gongdao, an antivirus expert at Jiangmin, said on Monday.
"More than 24,000 types of viruses were detected during the week," he said.
He said computer users should be more aware of viruses that could be passed on through movable disks.
Another antivirus company, Kingsoft, alerted the online community to a new virus it dubbed the "ultimate killer to antivirus software".
The virus, a kind of Trojan, is capable of hijacking all kinds of antivirus software when it successfully attacks a computer.
"It will also automatically search the keywords, including 'antivirus, Kingsoft and Kaspersky', and coercively close the programs, Li Tiejun, an antivirus software engineer of Kingsoft, said.
"The virus has been supported and spread by a group of people who have developed a systematic and standardized business operation to make profit," Li said. Virus controllers could detect the IP addresses of each computer, he added.
The new virus, which affected about 40,000 computers a day, will remain a critical threat to many computer users even after the holiday, Li said.
According to the latest survey conducted by the Ministry of Public Security, China has encountered a rising Internet security problem over the past three years, mainly triggered by a growing number of profit-driven computer virus writers, hackers and illegal traders.
Some 65.7 percent of 15,000 companies polled had suffered Internet security problems from May last year to May this year, 11.7 percentage points higher than before.