This appears to be problem with the home.tpl possibly not loading. So this would fall into the installation category. This mod will not cause what you are seeing unless you have moded or overwrote some other files from the cart.
I highly doubt this was displaying like this before by simply [adding] the code for this mod to the template outlined in the instructions?
Here is the snippet from my cart.tpl, sorry about the notes but I do this to help me know why this code is in place; helpful during future upgrades and troubleshooting too:
Starts at line 92 or so.
{* L92 Skin1/customer/main/cart.tpl code below added to display continue shopping button on pages *}
<TD align="right"><TABLE border="0" cellspacing="0" cellpadding="0" onclick="javascript
: self.location='home.php'" style="cursor: pointer;" valign="middle">
<TR><TD>[img]/skin1/images/but1.gif[/img]</TD>
<TD class="Button" valign="middle" nowrap><FONT class="Button">Continue shopping</FONT></TD>
<TD>[img]/skin1/images/but2.gif[/img]</TD></TR>
</TABLE>
{*end of code for continue shopping button*}
Hope it helps Good luck.
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