That looks like your apache log, not your php error_log.  It is just showing that some of the files being requested do not exist.  Check for your php error_log. 

Sorry, didn't work. 

Have very little idea about php, so this is bound to be wrong :-?

Web host is 1&1 and their FAQs imply that I don't have access to a PHP error log, but I might be able to create it http://faq.1and1.com/scripting_languages_supported/php/8.html.  This is beyond me!  However, I seem to have generate some output by trying what they suggest so it might help, if not any ideas on how I get 1&1 code into Joomla to generate error log. 

This is what site now reads,

error_reporting(0); $old_error_handler = set_error_handler("userErrorHandler"); function userErrorHandler ($errno, $errmsg, $filename, $linenum, $vars) { $time=date("d M Y H:i:s"); // Get the error type from the error number $errortype = array (1 => "Error", 2 => "Warning", 4 => "Parsing Error", 8 => "Notice", 16 => "Core Error", 32 => "Core Warning", 64 => "Compile Error", 128 => "Compile Warning", 256 => "User Error", 512 => "User Warning", 1024 => "User Notice"); $errlevel=$errortype[$errno]; //Write error to log file (CSV format) $errfile=fopen("errors.csv","a"); fputs($errfile,"\"$time\",\"$filename: $linenum\",\"($errlevel) $errmsg\"\r\n"); fclose($errfile); if($errno!=2 && $errno!=8) { //Terminate script if fatal errror die("A fatal error has occured. Script execution has been aborted"); } }
Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /homepages/7/d183703408/htdocs/interaktiv/cms/errors.php:11) in /homepages/7/d183703408/htdocs/interaktiv/cms/index.php on line 66

Will do.  Also, think I might have got the php error log working with 1&1 php

heres the output

http://www.interaktiv.co.uk/errors.bak.csv

that is the php error logging, however those are only notices which will not cause blank screens.  If you try it again do you see a fatal error in the log?

No Fatal.  Ran several times an all are notice.  I pasted the script into the very top of the index.php file!

Is there somewhere else that would be better?

created .htaccess file in joomla folder but this simply killed the backend as well  .  Have sent details as PM.