Go to ~/Library/Caches/com.apple.appstore
Move the Cache.db file from the com.apple.appstore folder to the Trash.
Now go to /Library/Preferences/System Configuration
Move the NetworkInterfraces.plist file from the System Configuratin folder the Trash.
Retart your Mac.
~ (Tilde) character represents the Home folder
That's the wrong library for the Caches folder. The convention of using a tilde in a pathname:
means that it applies to your user account and means the Library folder in your user home folder. The user's Library folder is hidden in Lion; to get to it, hold down the Option key, and in Finder select the Go menu. The Library for your user will appear there. Select it, and then look in the Caches folder.