Amazon.com recently updated their javascript, and it\'s causing problems with some Opera browsers.
Their browser detection code looks like so, but it\'s faulty:
It is much better to detect javascript capabilities rather than browser userAgent.
ie DOM, XmlHttpRequest, eventing model (event.target vs event.srcElement), ActiveX, Java etc
By focusing on the API functions that you will require, rather than a target browser you will create a more robust set of scripts, and inevitably less special casing.
This link here at opera will probably tell you more