Don’t worry your not the only one. Its a known problem that only Microsoft has recently officially acknowledged via their Knowledge Base. Unfortunately at this time of writing Internet Explorer 11 doesn’t play nice with CRM 2011. You will find that you just get a 404 error after logging into your CRM system. No one knows if Microsoft is planning to fix this, I REALLY hope they do, as yet again THEIR own browser is breaking THEIR own products (remember the whole Outlook Web Access thing as well). Well fortunately there are a couple of workarounds to this problem, so if you happen to live on the bleeding edge, fear not!