looking at the source of your cart, the image src is being set to:
../images/images/hair75.jpg
<img src="../images/images/hair75.jpg" alt="Product thumbnail" class="eC_ProductThumb">
it looks like the add to cart button is already adding the path, the cart code should be:
<img src="<?php echo $californianatural->DisplayInfo("Thumbnail"); ?>" alt="Product thumbnail" class="eC_ProductThumb" />