is loopback starting?
check on the boot to see if it brings up lo
login as a standalone user and type
ifconfig (in case you missed it at boot)
if nothing shows then something is up
try typing ifconfig lo up
then ifconfig again if something shows up your halfway there
now if you see lo then that should end all your problems just vi /etc/rc.d/<something here like local> and add
ifconfig lo up
at the end, this will make sure lo comes up before you try to login
save the file and restart and all should be cured.
If your still having problems with lo then try re-compiling your kernel and add loopback support in the network optionsy bit