If you aren't experiencing the shutdown problem, but want to be certain you dont have the virus (which you probably do not), go to the Windows Find function (Windows Key + F) and put "Msblast.exe" into
the search line. That's the name of the program causing the problem.
If you do have the virus and cannot get the PC to stay on long enough to get the download, on Windows XP, do this:
If you are using a cable modem turn it off first. If you dial in, don't do so until you have done the following.
Start your computer normally, and right click on your My Computer icon (either on your desktop, or click on Start and then you should have a my computer icon there you can right click on...) then select 'Manage'.
You will see 'Services and Applications' on the left side of your screen. Click on Services and Applications, then click on Services. On the right, scroll down to the 'Remote Procedure Call' service and double click on it.
After you double click, you will get a message box. Go to the recovery tab. Under the listed things, change the selected action to Take No Action (first failure, second failure, subsequent failures).
Then connect to the net, launch Internet Explorer, then go to Tools| Windows Update. Let it scan your PC and tell you what critical updates are needed. (The Windows XP updates are in a separate category, and you don't necessarily need those. The security related ones all appear in the critical update category.) If you use a cable modem, you may need to reboot your PC after you have turned it back on.