Some of you have reported issues with blank pages if your posts are too long or contain too many comments. I had the same problem with disappearing posts until Rob in tech support at Liquid Web helped me to resolve the issue. I tried Abel's fix over at http://www.undermyhat.org/blog/2009/07/sudden-empty-blank-page-for-large-posts-with-wordpress/ but I had no success.
Then Rob came up with the solution after about 45 minutes of troubleshooting. The fix is to increase the memory limit in your wp_settings.php file which is found in your server root. The number below worked for me! I'm a happy camper now. :)
if ( !defined('WP_MEMORY_LIMIT') ) define('WP_MEMORY_LIMIT', '48M');