It’s a red cross 
Sure… Without RPC you won’t have even Windows running…
Can you try to repair your installation?
Go to Control Panel > Add/Remove programs > avast! antivirus > Remove
Then choose Repair function in the popup window (Repair).
If this does not help, can you uninstall / boot / install / boot again?
Do you have any other antivirus installed in your system? Did you have in the past?