Although FF users (incl. me) may disagree, it is true.
In a business environment, FF is not an optimal browser. If the business is pretty much Microsoft-dependent on their software (desktop and server OS), FF is not really ok with IT admins.
Firefox doesn't obey
Group Policies, which means people can install FF and things like proxy addons without any restrictions, and boom: instant security nightmares. If Firefox is to succeed in an MS-powered business environment, someone needs to come up with a way for it to follow Group Policy.