try changing the dynamic code to:
<?php echo $row_WADAinventory_tbl['Photo_1_Thumb']?'<a class="thumbnail" href="#thumb"><img src="' /Auto_Dealers/' . $row_WADAinventory_tbl["Dealer_Name"] . '/images/' . $row_WADAinventory_tbl["Inventory_ID"] . '/' . $row_WADAinventory_tbl['Photo_1_Thumb'] . '" border="0" /><span><img src="/Auto_Dealers/' . $row_WADAinventory_tbl["Dealer_Name"] . '/images/' . $row_WADAinventory_tbl["Inventory_ID"] . '/' . $row_WADAinventory_tbl['Photo_1_Resize'] . '" alt="" border="0" /></span></a>':""; ?>
it's the document root that is causing the issue
to put code in blocks see misc.php?do=bbcode