[prof_hobart]

Can't speak for the internals of that organisation, but the main reason I've come across for corporates still being on IE6 is the very real cost of migrating.

Many legacy web applications were built to work on IE6, and changing to a more modern browser can subtly, or completely in some cases, break these critical apps. It may be a pain for users when their favourite social media site looks rubbish or doesn't even run in IE6, but it's nothing compared to the finance department not being able to run their end of year reports because one screen in their GL system doesn't render properly in Firefox.

And it costs money firstly to test every single function of every single app that your business uses, and secondly to fix those places where it breaks (especially when it's an external vendor's application). That time and money can often be better spent doing one of the thousand other things that are making demands on the IT budget. Most companies are slowly making this transition, but unfortunately it's not just a case of saying "This browser it better/more secure than that one. Let's upgrade".