OpenSearch suggestions not working in IE 8 in a guest account

[jdee]

In IE 8 on Vista, Dubsar is added to the browser's search engine list. All works just fine, except that suggestions do not work. When a letter is typed, the browser simply reports an error. Strangely, in a non-guest account (with administrative privileges), autocompletion of suggestions works just fine. It also works in every browser that allows customization of search engines, except for Camino on OS X. There, searching works, but autocompletion does not. Notably, all functionality works very well with Google Chrome 8 and Firefox 3 on all tested operating systems. Safari does not allow customization of search engines.