www.ulster-scots.biz and www.irishteatowels.com

Getting these messages in my cache folder on both sites above.

[05-Feb-2013 08:28:26] PHP Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home2/irishisb/public_html/ulster-scotsbiz/isa38/includes/modules/product/collect_info.php on line 512

(for www.irishteatowels.com it references line 541

Do anyone know what is causing these ?