Blah, blah, blah...ignore everything else I wrote (unless you have a proper PHP solution, then cough it up!)

Ok--the only solution I can come up with, is just a simple javascript back. If the user has javascript disabled, then oh well.

Nothing else works 100% or even 60% properly for me.

You can see the old version of the button link above, here's the new version:
<div class="buttonRow back"><a onclick="javascript:history.go(-1)"><?php echo zen_image_button(BUTTON_IMAGE_CONTINUE_SHOPPING, BUTTON_CONTINUE_SHOPPING_ALT); ?></a></div>


Notice.. I didn't include <a href="...

The reason is, I think it looks a bit sloppy, so I just buried the function inside an onclick function.

If I clean up my store URLs, I might do this to a lot of buttons if I'm too lazy to fix internal links...

Sneaky, sneaky, sneaky...