PHP Warnings in apache logs

[ghost]

While checking dedicated php_error.log, I've found that it full of php warnings coming from Phychostats. Examples:
[19-Jul-2011 06:38:44] PHP Warning: urlencode() expects parameter 1 to be string, array given in /users/home/cs-iptcom-net/stats/includes/ofc/open-flash-chart.php on line 180
[19-Jul-2011 06:38:48] PHP Warning: urlencode() expects parameter 1 to be string, array given in /users/home/cs-iptcom-net/stats/includes/ofc/open-flash-chart.php on line 180
[19-Jul-2011 06:38:51] PHP Warning: urlencode() expects parameter 1 to be string, array given in /users/home/cs-iptcom-net/stats/includes/ofc/open-flash-chart.php on line 180
[19-Jul-2011 06:40:49] PHP Warning: urlencode() expects parameter 1 to be string, array given in /users/home/cs-iptcom-net/stats/includes/ofc/open-flash-chart.php on line 180
[19-Jul-2011 06:43:34] PHP Warning: urlencode() expects parameter 1 to be string, array given in /users/home/cs-iptcom-net/stats/includes/ofc/open-flash-chart.php on line 180
[19-Jul-2011 06:43:34] PHP Warning: Invalid argument supplied for foreach() in /users/home/cs-iptcom-net/stats/includes/ofc/open-flash-chart.php on line 325
[19-Jul-2011 06:44:00] PHP Warning: urlencode() expects parameter 1 to be string, array given in /users/home/cs-iptcom-net/stats/includes/ofc/open-flash-chart.php on line 180
[19-Jul-2011 06:44:00] PHP Warning: Invalid argument supplied for foreach() in /users/home/cs-iptcom-net/stats/includes/ofc/open-flash-chart.php on line 325
[19-Jul-2011 06:44:24] PHP Warning: urlencode() expects parameter 1 to be string, array given in /users/home/cs-iptcom-net/stats/includes/ofc/open-flash-chart.php on line 180
[19-Jul-2011 06:44:24] PHP Warning: Invalid argument supplied for foreach() in /users/home/cs-iptcom-net/stats/includes/ofc/open-flash-chart.php on line 325
In every day logs there are several hundreds such errors, can you provide fix for this?