I upgraded one of our servers from SLES SP2 to SP3 last night. Since then, people using Windows XP computers (we still have a few) and a Windows 2003 Server can't login to the Linux box.

It gives a System error 1326: unknown user or bad password.

Windows 7 and Windows 10 have no such problem.

Can anyone give me a steer as to where to look / what to do?

Many thanks