Your store cart file looks like it has been corrupted, possibly by making edits to it with eCart 4 then upgrading to eCart 5.
You should reload the default version of this file from the downloads area. This should get it all back in order and then make edits only with eCart 5. When I try this it seems to get it all back in order. Please post back and let us know if you have any further troubles with this.