Fatal error: Call to undefined method wpdb::get_blog_prefix() problem

If you just upgraded to WordPress 3.0 and is using the db cache reloaded plugin, you might encounter the following error when you try to access some pages in your admin:
Fatal error: Call to undefined method wpdb::get_blog_prefix() in …/public_html/wp-includes/user.php on line 445

The fix is pretty simple:

1. disable the plugin.
2. manually delete the wp-content/db.php
3. delete the offending plugin
4. if you must need to use a caching plugin, I believe there is a patch around (google is your friend). the patch should be good until the plugin developer updates the plugin to be compatible with wordpress 3.0