If you got a message says that “NT/Authority is initiating the RPC to shutdown the system and the system will close after a countdown of 50 seconds” then your computer is infected by Lovesan or (lovsan) the Blaster virus. This virus usually affect Windows XP and 2000.

To overcome this problem you need to download a patch to plug the security hole in the OS.  The Microsoft knowledge link of this patch files can be found here

The Cure:

• Remove the cable or switch the modem OFF
• Prevent system to shutdown on its own

Start->Run->services.msc
or
Start->control panel ->Administrative Tools ->services

• Look for ‘Remote Procedure Call (RPC)’ and double click it.
• Click on ‘Recovery tab’ and choose ‘Take no action’ for the 1st, 2nd and Subsequent failures.
• Click on ‘Apply’ and ‘ok’

• When you finish this the system might restart.
• After getting back to desktop again click start->run->(type)shutdown/c and ok
• Then run fixblast.exe file given here.
• Once that finishes, run the MS Patch which is relevant to your OS

Windows NT 4.0

Windows NT 4.0 Terminal Server Edition

Windows 2000

Windows XP 32 bit Edition

Windows XP 64 bit Edition

Windows Server 2003 32 bit Edition

Windows Server 2003 64 bit Edition

Restart after the Installation complete