Compuserve takes over TCP/IP ?
TCP/IP may be inactive.
Apple
Control Panel
TCP/IP
Close it and it will ask to be made active, choose "OK".
One or all of the Open Transport/Remote Access extensions are off or not installed.
Zap the Pram (Parameter Ram Zap)
Special
Restart and hold down ALT & APPLE & P & R).
If it still doesn't work the Pram battery may need changing.