wp-cron-oneshot folder to the /wp-content/plugins/ directory.A. This is a troubleshooting plugin. This plugin will add a task to the wp-cron queue which will trigger an immediate wp-cron run. This helps if you ever need to troubleshoot access-denied type errors in your Apache access logs. For example, a 403 error like the following: xxx.yyy.com - - [07/Dec/2010:11:27:42 -0500] "POST /wp-cron.php?doing_wp_cron HTTP/1.0" 403 5432 "-" "WordPress/3.0.1; http://www.example.com" This plugin will add a task to the wp-cron queue so you don't have to wait 12 hours until the next natural cycle.
A. It's scheduled to run immediately. To kick it off, all you have to do is navigate to another page within WordPress Administration and wp-cron will run. For example, just click over to the Dashboard or Posts screens. This will trigger an immediate wp-cron run.
A. Because wp-cron is not a true cron in the Linux sense of the word. There's no timer running in the background for wp-cron jobs like there is for Linux's cron. The mechanism is this: whenever someone clicks on your site (or you move between pages in wp-admin), then WordPress checks the wp-cron queue. If it finds a job there, it checks the current time. If the clock time is past the time that the job is scheduled to run, WordPress runs it.
A. The problem might have something to do with your .htaccess file. If you're filtering out certain user agents in your .htaccess, check for one that could be interfering with WordPress - things such as 'wordp' or 'press' or something. You can comment out portions of your .htaccess, then use this plugin to schedule wp-cron tasks so you can see if you've found the problem.