I am seeing a lot of these each day in my error log. Any thoughts on how to fix it?

[Fri Nov 18 07:03:29 2005] [error] PHP Warning: Invalid argument supplied for foreach() in /home/public_html/b2evocore/_class_itemlist.php on line 637

I searched four times changing keywords but couldn't find a relevant thread. Sorry if this has been posted before.

Heidi