A fast-spreading virus is infiltrating Hampshire firms wreaking havoc and costing the companies thousands of pounds.

The Sircam virus (technical name: W32/SirCam@MM) is thought to have been unleashed in Mexico about a week ago but quickly spread through Europe.

It does not delete files but randomly picks up a document from the person's hard disc and emails it to people in his or her address book.

The virus arrives as an email, usually from someone they know, and a cover message which says: "Hi! How are you? I send you this file in order to have your advice. See you later. Thanks." There is an attachment which, when opened, releases the virus.

Despite the bad English, the friendly feel of the message (and the fact it has come from someone they know) means many open the attachment without thinking.

Although not particularly harmful, it can send private and confidential documents to all and sundry. It can also cost companies hundreds or thousands of pounds to disinfect computers. The internet community has deemed the virus a Level 4 high risk virus (on a scale of 1 to 5 - low to high).

The McAfee antivirus site offers advice on how to rid your machine of the virus. Visit http://www.mcafeeb2b.com/naicommon/avert/avert-research-center/tools.asp#sircam.