Scoresia, its not the "blaster" virus.
Typically, the blaster virus would cause a machine to reboot in scheduled intervals.
If a machine is infected, the machine should still be able to be logged in.
Typical error of "System shutdown by NT Authority\System" message will be displayed.
Doesn't require format of the Hard drive.
In other cases, it will cause a machine to reboot every time the machine connects to the Net. If there are apps setup to autostart before login, and connect via internet, it would do this. Fix would be to disconnect the internet connection, and follow steps to "clean" the virus.