WM/Wallpaper is a Word macro virus.
Beside replication, the virus activates its payload on every 31th day of each month. At this time, it attempts to replace the Windows desktop's wallpaper with a picture of a skull. This picture is saved to "c:\windows\temp\sk2.bmp".
Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.
More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.
You may also refer to the Knowledge Base on the F-Secure Community site for more information.
It also modifies the "c:\autoexec.bat" and "c:\windows\win.ini" to perform the changes to the user's desktop.
Depending on the system time, it shows a message box with the same image and the following text:
The [PIRATE VIRUS] pillaged your computer!
The message box contains a single button labeled as:
GO BACK TO MS-WORD??