have you winbind running or have you manually typed the group information to the server?

then,
this does not get you rid of the errors, but you have homes share in basic.
with samba you can do even like:

[%U]
comment = Home Directory for %U
path = /home/%U
public = no
user = %U

to make automatically shares for all of your users in the style as in NT.

back to your problem.
you have
guest account = guest
on, which gives you the password prompt and you don't need that.

even if you decide, you don't want to use winbind, you may use samba.conf to map all your users!
it can be done with:
add user script

cheers,
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