Unable to log into Windows 7 PC - "The RPC server is unavailable"

Step 1: To start the RPC service, try these steps.

a. Start the computer using Windows DVD to boot to Windows Recovery Environment (WinRE) and select command prompt.

b. Type net start RpcSs and hit enter.

c. Type exit to close the command prompt.

d. Restart the computer and check the result.

Step 2: Check the registry entry for the service

a. Start the computer using Windows DVD to boot to Windows Recovery Environment (WinRE) and select command prompt.

b. On the command prompt, type regedit.exe and hit enter.

c. Look for the following entries:

d. Entry for Remote Procedure Call (RPC): Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\RpcSs

e. Entry for Remote Procedure Call (RPC) Locator: Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\RpcLocator

Important: Set REG_DWORD value to 2 for automatic start on RpcSs Set REG_DWORD value to 3 for manual start on RPCLocator

Very important: Modifying the registry incorrectly will cause serious damage to the computer. Backup the registry before you make any changes.

Reference: http://social.answers.microsoft.com/Forums/en-US/w7repair/thread/734dc03b-a795-4f08-aa32-84cf12b5e6be