If you can't fix it yourself, sending us these portions of the log files will help us figure out the problem. You can edit the Shopcart.ini file directly to change this. Templates are not just web pages, they can be other things like emails. When a template file is processed, it is read in from start to end. If it encounters a replacement rule, the replacement text is calculated, and that replaces the replacement rule.
Examples are below.
This feature only works if you run Shopcart version 1.0w or later. If there are items with only one size, do not include them in these lists. This can be confusing because it is a double negative. When you have decided how you want it displayed, put it all on one long line, and paste it into the size column on the cart table format page. You can also do this for color or another aspect of the products.