So many daft and dozy Corporates do what mixture says. It is a real pain.
The one thing I probably hate more than the IE-lovers is those who insist on using Microsoft Silverlight or Java Applets.
Silverlight, for those not in the know, being Microsoft's poor attempt at gaining marketshare from Adobe Flash. Basically a project doomed to failure before it started.
As for Java Applets ... well that's soooo last century ...
I remain happy with Adobe Flash for the time being .... until HTML5 matures a bit more and is more widely and robustly implemented on the browsers.
JavaScript is a bit over-hyped and over-used, but most of the time it doesn't do anyone any harm.