Software installers. Worse, operating systems installers.
Especially ones that work just fine with your pointer until the first reboot, then decide they know not of this strange "mouse" of which you speak and force you to use the "obviously no one will ever have to navigate this by keyboard! hah! hah! And if they're trapped without a pointer *certainly* they won't need the 'expert options' dropdown to work!" interface instead. Of course after I rebooted after the install completed, the pointer worked fine again. Hate. --s.
