Sometimes an error somewhere in the PHP simply leads to a white screen, no error message, nothing.
I just encountered another example of this.
After a major CVS update, settings.php contained the declaration var $show_scores twice.
This neither showed on the screen (everything just remained white), nor in the CompleteSearch error log, nor in the Apache error log.
After activating the PHP error log by adding the following lines to php.ini
log_errors = On error_log = "C:/opt/php5/error.log"
I found the following in the file specified as error log:
[29-Oct-2007 00:15:29] PHP Fatal error: Cannot redeclare Settings::$show_scores in C:\opt\cygwin\home\holger\completesearch\www\autocomplete-php\autocomplete\settings.php on line 152
IS THERE REALLY NO WAY TO GET THIS MESSAGE ON THE SCREEN ???
Note: the specific error just described (fatal error due to redeclaration) does only occur under PHP 5, under PHP 4 everything works fine (the redecleration seems to be ignored).