Hey there,
I have searched the forum and found multiple threads on the issue. However none of them had a clear fix for me.
Just earlier this day I was playing crpg with no issue and have been doing so for a month. I had just carried out the minor update to the new version and played for around half an hour. I then switched to a family steam account in order to play a different game (this is not a new occurence, done this many times in the past). I log back into my original account, but now when I log into a server with my current characters I get the above error message instantly and get kicked.
I have checked my registry for warband, the key is exactly the same as that steam shows me.
Just to clarify, I only have one warband cd-key which I play on my original steam account.
Cheers for any help you can provide.