"Cannot use a scalar value as an array" error
Sometimes these error messages come up on my sites if cron is run while the site is in maintenance mode. I'm guessing the maintenance mode template for our site has something to do with it, but it could be a variety of things.

When cron runs, it is still running through Drupal's theme system, so you probably have something awry in either your theme or one of your custom modules. Does this happen every time cron runs, or just sometimes?

A final troubleshooting step would be to install elysia_cron and run each cron task individually to see which one might be causing all these errors.

See also: Warning: Cannot use a scalar value as an array