Hi Craig,
Yeah there is some information on that here:
http://www.mojoportal.com/security.aspxI hope you have a way of connecting directly to the db to solve this problem. First set it back to not require encryption your old password shoud still be there and you should be able to login again.
Then login as Admin. Its been a while since I've reviewed this functionality but I think what you need to do is reset your admin password while you are still logged in after making this change this will remove your clear text password and create a random one encrypted, once you login again you can change it to what you want.
To be safe you could make a second admin user while still logged in after this change, then on a different computer make sure the new admin can login before you logout in case you need to revert.
Then again as long as you have way to connect directly to the db you can always set the site back to non encrypted and key a new password in the db if it doesn't work.
The current model uses one way encryption so you can't decrypt it. When a user logs in it encrypts the password he types and compares to the encrypted password in the db.
In the future I may change to 2 way encyption which would allow password recovery. This has been more challenging to implement in the past because you have to store the private key somewhere safe. In .NET 2.0 things are little easier we could use an RSA Key pair and encrypt the keys in the web.config using a machine key.
Hope that gets you back in business.
Cheers,
Joe