Has anyone been in a similar situation:

On one of the sites I've made with Atahualpa, all Atahualpa settings have been reset. Can the site have been hacked?

It seems like the widget areas I've defined is still there, but all other settings including CSS inserts, are gone.

I do have a backup of the settings from February 1st, but this doesn't seem good.

Any similar experiences?

I was able to restore the settings from the backup file, and adding the changes I made since the backup, but I'm still wondering how this can happen?

Will now make it a habit to use the "export settings" function every time I make changes.

The only way I've seen the settings reset is by pressing the 'Reset all settings' button

Yeah, and that possibility is almost certainly ruled, unless some cracker has gained access to one of the admin accounts.

We will contact the host to see if they have any relevant information.

Take a look at the plugin 'wp dbmanager' if you can get it to work you can schedule automatic database backups.

I have Austin Matzko's WP DB Backup plugin doing that already, but thanks for the tip :-) It works okay, even though it's beginning to get old. I have restored DBs from it though.

I see that the one you mention are more up to date.