It's not the fault of Win10. I just had to be forcibly converted to Win 10 and my "large" main can log in just fine (computer up and died, so I had to bring my disks across).
I suggest as a possibility that either the *.icfg or *.xml file for the toon has been corrupted. If there are backup copies, recopying them would be something to test.
You could also try copying the icfg and xml files somewhere else and launch the main toon without it's setup stuff (I suspect that would work, but it's clearly not a satisfactory long term solution.)
Looking in the client.log file and comparing the successful to unsuccessful logins would also help assign "blame".
Hope these ideas help.
I suggest as a possibility that either the *.icfg or *.xml file for the toon has been corrupted. If there are backup copies, recopying them would be something to test.
You could also try copying the icfg and xml files somewhere else and launch the main toon without it's setup stuff (I suspect that would work, but it's clearly not a satisfactory long term solution.)
Looking in the client.log file and comparing the successful to unsuccessful logins would also help assign "blame".
Hope these ideas help.
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Remembering Tyneetryk
Phaedreas Tears - 15 years old and first(*) of true neutral guilds in Atys.
(*) This statement is contested, but we are certainly the longest lasting.
<clowns | me & you | jokers>