My server error log has thousands upon thousands of entries for the following error message:
[10-Mar-2012 00:22:41] PHP Fatal error: Call to undefined function w3_url_format() in /home/fontlife/public_html/wp-content/plugins/w3-total-cache/lib/W3/Plugin/PgCacheAdmin.php on line 213
I think I fixed the roblem by adding the following line to the top of the PgCacheAdmin.php file:
require_once W3TC_INC_DIR . '/functions/url.php';
The function w3_url_format seems to be defined there.