It sounds like you need to bring over the machineKey setting from the web.config on the old site, this controls the encryption key used for storing passwords on a default DNN configuration. 

Make sure you backup the current web.config, as any accounts created with the new DNN site won't be able to login after you reset the machineKey to the old site's setting. I'd recommend logging in as host, then change the machine key, open up a new browser (if you're using firefox as host, then open up IE) and try logging in as an older user and the passwords should work. You'll then want to manually update / reset any accounts which were created by the new DNN system (i.e.. during setup, or manually via the admin > users page)

Hopefully this is enough to restore the old passwords of your users. Let me know!

Oliver,

Thank you; I had forgotten about the MachineConfig key machineKey! Do I ever feel like a rube.

I copied the key into the new site's web.config and the original passwords started working again. As you mentioned, my own SuperUser account no longer allowed me to log in, but I have access to our site's SQL server so I simply opened the old and new sites' "aspnet_Membership" tables and copied my UserID's values for the "Password" and "PasswordSalt" fields from the old to the new. Worked like a charm. We only had two [new] User accounts set up at the time, so I did the same for the other one as well and we are back in business.

Gratefully,

Kurt

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