See this news article posted by rippinchikkin Is There A Rootkit Stashed In Your Boot Record?
Here's a fix:
From the recovery console, advised Elia Florio, another Symantec researcher, users can run the "fixmbr" command to remove the rootkit. "To help prevent similar attacks in the future, and if your system BIOS includes the Master Boot Record write-protection feature, now is a good time to enable it," Florio recommended
Not that there are exactly a lot of systems infected at about 5000, but it could be a meanie to get rid of. I guess one would only know if ones system no longer booted. It seems it's "acquired" by visiting certain "host" sites that have been compromised.
I haven't checked right now, but I can't remember that my BIOS has a MBR write protection feature. At least it can be gotten rid of though.
"The great majority of mankind are satisfied with appearances, as though they were realities, and are often more influenced by the things that seem than by those that are." - Niccolo Machiavelli