it asks me to logon with my password over and over again.
Try some procedures:
1. Configure the way you connect to Internet (dial-up or DSL)
avast settings > Connections (Basic) and (Advanced)
2. See the Internet Settings for connections (generally: Tools > Options > Connections): do not dial, dial the standard connection, by LAN, etc.
3. Post here your email account settings (do not post your password and use 'generic' usernames). We can guide you...