Warning Undefined Variable on Win - PHP 4.0.6 via Apache

I keep getting a Undefined variable on unused form elements after they have been posted. For instance i have a form Form Element Chem_id ( drop down) Form Element freetxt ( text box) Query String A B C D to search for products via letter both the form post and the querystring go to the same page. If the querystring is use i get the Warning: Undefined variable Chem id and freetxt error mgs but if i use them ..it works fine... Is this a bug or do i need to change a setting in the php.ini file Any help would be greatly appreciated. Wes wes@wesdev.net