I just ran the version 1.8 upgrade. The first time I entered the incorrect username and password but the wizard still ran. Then once everything was done I tried to open the site and go a database login error. After changing the user and password on the backend the site came up, but was unable to log into the website with the admin account. I copied the files back over again and tried to run the upgrade again, this time it reported that I already had version 1.8. So I deleted the database and restored the 1.7 database. Restarted the upgrade process this time using the correct login and password for the Database. And now the site works just fine.
Dunno if thats a bug or not, but thought that I would pass it along.
yes i do this, check the global settings --> Other --> 'Usernames' enabled and now i can't acces to control panel, what can i do for disable this option ?