Linux machine is in a windows domain, but domain logon isn't working

Solution 1:

Try changing in your smb.conf:

idmap backend = ad

for:

idmap backend = rid

And restart your samba services (winbind mainly). If it still doesn't work, try this:

Stop samba services
Delete samba database and cache files (usually under /var/lib/samba, tdb files).
Run net ads join again
Start samba services

Which samba version are you using?