This is a virus detection. Viruses are programs that self-replicate recursively, meaning that infected systems spread the virus to other systems, which then propagate the virus further. While many viruses contain a destructive payload, it's quite common for viruses to do nothing more than spread from one system to another.
The worm harvests email addresses from the MSN Messenger.NET contact list. It sends itself to found recipients via HOTMAIL.COM. It copies itself to shared folders:
Use current engine and DAT files for detection and removal.
Modifications made to the system Registry and/or INI files for the purposes of hooking system startup, will be successfully removed if cleaning with the recommended engine and DAT combination (or higher).
But in some particular cases, the following steps need to be taken.
Please go to the Microsoft Recovery Console and restore a clean MBR.
On Windows XP:
On Windows Vista and 7: