What a terrible practice. Microsoft appears innocent by claiming it is currently investing a solution.
Bing Is Now Your Default Search Engine On IE6, Whether You Like It Or Not
The Next Web reports that users of Internet Explorer 6 are being forced to use Bing as their default search engine — even if they’ve manually switched their preference to another search provider, like Google. Attempts to switch the browser to something other than Bing result in an error message.
While the vast majority of users affected probably won’t even notice the change, some are beginnig to complain (you can find threads in Google’s forums here and here). Microsoft has confirmed the issue to Search Engine Roundtable, explaining that it is currently investigating a solution. (Source: Techcrunch)
By the way Bing is currently my 2nd top referrer.