Initially on February 3, and on the third of each month after, the Nyxem virus (Sophos W32/Nyxem-D) is designed to automatically overwrite files such as the access database, .doc files as well as Excel and Powerpoint files (.pps and .ppt) in infected computers and also spread via network connections.

While most antivirus companies released a specific fix nearly two weeks ago, a common trait of the virus is disabling or corrupting antivirus programs.

Sean Richmond, senior technical consultant with antivirus firm Sophos, said only a small number of infected computers had been discovered so far. Richmond said from the behavior of the virus to date, it looks like it was designed by someone throwing a tantrum - not as a specific and malicious tool.

"Nyxem is not designed for financial gain, nor does it offer more advanced techniques like buffer overflows ... it appears to be just an attempt to do damage and I don't know whether it was designed by someone wanting to be a nuisance," Richmond said.

"It does not install remote access tools or open backdoors which is far more common nowadays with people attempting to get control of system; all Trojans spammed out lately aim at hooking into IRC and allowing remote control.