Something in the background (I'd guess the Blaster or one of its varients) is terminating your RPC.
Try this:
In many cases, on both Windows 2000 and XP, changing the settings for the Remote Procedure Call (RPC) service may allow you to connect to the Internet without the computer shutting down. To restore Internet connectivity to your PC, follow these steps:
Click Start > Run. The Run dialog box appears.
Type:
SERVICES.MSC /S
in the open line, and then click OK. The Services window opens.
In the left pane, double-click Services and Applications, and then select Services. A list of services appears.
In the right pane, locate the Remote Procedure Call (RPC) service.
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CAUTION: There is also a service named Remote Procedure Call (RPC) Locator. Do not confuse the two.
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Right-click the Remote Procedure Call (RPC) service, and then click Properties.
Click the Recovery tab.
Using the drop-down lists, change First failure, Second failure, and Subsequent failures to "Restart the Service."
Click Apply, and then OK.
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CAUTION: Make sure that you change these settings back once you have removed the worm.
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