Search Engine Land reports a bug in Internet Explorer 6 is forcing users to use Microsoft's new Bing service as the default search provider. Since Bing launched, the search provider was automatically switched to Bing and when a user tries to switch from Bing to Google or another search engine, it doesn't allow them.
A Microsoft representative sent me the following statement:
We’re aware of the issue with IE6 and Bing and are investigating a solution. This issue is not impacting IE7 or IE8 users. We respect user choice on search providers in IE and all browsers, and designed IE to enable that choice. We will provide an update soon on this issue, and we apologize for any inconvenience it has caused. In the meantime, we encourage customers to upgrade to IE8 here. Alternatively, Firefox users can install the add-in for Bing here.