Dave, Torben, Thank you very much for the replies.

Torben, I restrict login to https which avoids the doube sign-in issue and prevents sending of cleartext passwords.

I have a heavily customised config.tcl file that I spent ages on so I will have to trawl through and look for any omissions against a new example file.

You are almost certainly right that this is a case of misguided misconfiguration!

I'll have another go.