Why crm 2011 not load in Firefox 11 successfully?

Hi,
Mozilla Firefox is a very powerful web browser but it is creating a problem with CRM 2011. When I connect to the Microsoft CRM site, it shows credentials prompt error of the user. I tried to solve it by updating web browser but nothing changed. I am worried why CRM 2011 not load in Firefox successfully and occur this problem. Any information related to it please.
