'Column 'Category' in where clause is ambiguos' breaks my page

I was trying to make products_search.php work and I broke products_results.php. I get the following error when I enter a known Category 'Boulders' at http://outofchaos.net/gsc/www/products_search.php and when I use the Products dropdown - http://outofchaos.net/gsc/www/products_results.php?Category_ID=6
When I uploaded products_search.php to my testing server, I clicked 'yes' to move dependent files. Now my products_results.php on my testing server when accessed thru the dropdown menu is giving me the same 'Column 'Category' in where clause is ambiguous' message. I restored the working file but still same problem. I did not upload dependent files to the remote/live site but I did just upload products_search.php by itself to see how it acted there and same thing! dropdown product/category search still is broken there. http://outofchaos.net/gsc/www/products_results.php?Category_ID=6 . I'm hoping the answer to the error for search will allow me to fix whatever is screwing up products_results. Couldn't see what else could have changed in that I only uploaded products_search to live server to muck up the product_results page.Help please.