After updating to WP 2.5, and making sure everything worked I then changed themes to the K2 theme. I was able to log in and everything worked immediately.
Now, 14 hours later I get a Fatal error: Call to undefined function: wp_register_sidebar_widget() message.
Would anybody be able to help with this and I'll tell you upfront that I'm really a novice with no programming experience.
Thank you for your help in advance.