At my Fortune 500 company, permission to use Firefox is only granted to programmers who can convincingly argue that they need it for compatibility testing on Internet-facing applications. It's IE6 for everything else. The reason is that Firefox is a security risk(!).

Because the people that do desktop support don't want to support more browsers than the minimum possible. I'd bet a decent proportion of desktop support calls are about 'problems with the internet' (read: browser) and starting every one of those call with "are you using IE or Firefox?" would most likely get answered with: "I dunno! I want to use Google!"

heh

"we got a problem here, uh yeah, the website is down"

http://www.thewebsiteisdown.com/

In some cases, because the company in question feels you shouldn't need external access at work.

If the company doesn't allow external internet access, it isn't relevant to anyone deciding what browsers their website should support.

Just because an employee shouldn't access the internet at such companies, doesn't mean he/she doesn't