A Bing thread has two complaints from webmasters on Microsoft's newish crawler, MSNBot 2. The bot, in some cases, might be adding a pound sign (#) to the end of the URLs.
Now, this might not be the fault of Microsoft, it might be an issue with links and/or the web site's being crawled. But there are now two people reporting it and MSNBot 2 is a beta bot that may have issues, as Microsoft did allude to.
On June 29th, Brett from the Microsoft team did say, "I'm getting our crawler team to look at this. I'll update you as soon as I've heard back." But since then, we have not heard back.
Of course, there are ways to force the bot to the correct URL. I.e. block the # signs in your robots.txt or 301 redirect those URLs to the main URL.
Forum discussion at Bing Help.
