Solution
Thanks to 4ice for the tip. I very much stumbled upon the answer to this one.
The problem is in the file ./scp/js/ajax.js near the end of the file.
This:
}<STRONG><s>**</s>,<e>**</e></STRONG>
};
Http.Init();
Needs to be changed to this:
}
};
Http.Init();
Who knew a comma could cause so many problems...
Tested in IE... Now no error and Canned response works!!