Our Red Hat Linux server is having problems logging established users onto the network! There was a proxy server problem the previous day and the proxy setting was changed? Any Ideas what could be happening. The night before it work and then in the morning half of the users couldn't log on?
Then you should first try to check what kind of error does the
smbclient -L //localhost -U valid-user
If this doesn't give you any clues about the problem, check logs, to find where they are placed do the following:
$ grep '\<log\>' /etc/samba/smb.conf log file = /var/log/samba/log.%m log level = 2
check the generic log file (in this example