I have had the same problem, go to the link
http://securityresponse.symantec.com/avcenter/FixBlast.exe
http://securityresponse.symantec.com/avcenter/
venc/data/w32.blaster.worm.removal.tool.html
and it will remove this problem automatically, and if you want to remove it manually than do the procedure below, Restoring Internet connectivity and preventing the computer from shutting down In many cases, on both Windows 2000 and XP, changing the settings for the Remote Call Procedure (RPC) service may allow you to connect to the Internet to obtain downloads, and will stop the computer from shutting down.
1. Click Start > Run. (The Run dialog box appears.)
2. Type:
SERVICES.MSC /S
in the open line, and then click OK. (The Services window opens.)
3. In the right pane, locate the Remote Procedure Call (RPC) service.
CAUTION: A service named Remote Procedure Call (RPC) Locator exists. Do not confuse the two.
4. Right-click the Remote Procedure Call (RPC) service, and then click Properties.
5. Click the Recovery tab.
6. Using the drop-down lis
Using the drop-down lists, change First failure, Second failure, and Subsequent failures to "Restart the Service."
Click Apply, and then click OK.
Hope it'll work for u.