duplicate tables and login problem

[pabirds]

Somehow I have duplicate tables in my Joomla database. One set is preceded with jos_ and the other with pso_.

When I installed Joomla (months ago) I set the precursor to pso_.

I recently moved the site to a new host (the new host did the migration). I have been logging in okay since the migration.

But, today I can't login to the backend. All I get is a white screen. I don't even get the login screen. Yesterday I set all of the permissions to default using the AdminTools plugin. But I was able to login after that.

The front end works fine.

After looking up the login problem, I checked the configuration file, but its settings were fine (cookies, etc.).

So...

Is it safe to delete the jos_ tables?

Any troubleshooting tips for the login problem?

[wwhite]

Look under global config - server - database settings to be sure which tables your site is pointed to
back up back up first, then delete what you dont want
I assume you are logging into the back end again

[pabirds]

I can't login, so I can''t get to the global settings. Is there a file with these settings that I can manually edit?

[wwhite]

should be in configuration.php
public $dbprefix