Re: Same old, same old...
Microsoft have long form for ignoring their own policies and guidelines. From where the put data files (hint: never in the windows or program files paths) all the way through to ignoring regional settings when it suits them (everyone is American) and of course the user interface guidelines. At one point in time, Microsoft clearly put a lot of thought and work behind their user interface guidelines, only for the rest of Microsoft to utterly ignore them.
Office: The damn thing includes it's own window rendering mechanism, utterly bypassing the Operating System. Seriously, a shitty application (set of) from the same vendor as the Operating System choosing to ignore the Operating System and to render the application how it feels. With some exceptions, an application should adapt the display to fit that if the windowing environment it sits in, however Microsoft's Office applications choose not to do this and instead recreate the damn UI from scratch every time - with the usual inevitable results of inconsistency and inefficiency.
UI design: As a crass generalisation, if the user has to think (or worse, refer to instructions), then the UI is a failure. Unfortunately Microsoft have taken this to heart so much that there is no bloody user interface left to think about because there are no functions remaining that the user can interact with. Microsoft also pioneered moving "mystery meat navigation" into the Operating System, replacing buttons with weird hieroglyphs with hover-over text that may or may not show (and never shows in a touch controlled system) all the while keeping much of the functionality as non-customisable (i.e. unable to be sensibilised or rationalised by default) and removing choice from the user. One of the other key aspects of a good UI is consistency... and Microsoft fail on this in pretty much every place they can - through control order, text use, buttons vs weird non-links, ignoring the user's configuration with regards to which fucking web browser to use (sometimes), window behaviour (the control panel replacement apps are sort of the same application, navigating to one closes another, except when it doesn't), the two start menu search interfaces (not least: no, I do not want to now, nor ever to, user cortana). /rant
Windows XP: An old one (but a fine example of Microsoft stupidity), but rather than extend and enhance the windowing functions in the Operating System, Microsoft chose to overlay a new skin on top. A feat of pure genius that entailed an application's windows being drawn twice: first in the default, underlying (Win2000) look and feel and then to draw over the top the Windows XP look and feel. This stupidity didn't cause problems at all [sarcasm] and was exceptionally daft because there were third party applications available at the time that would intercept and replace the standard windows drawing calls and replace them with different ones all without having to draw the windows twice.