What Turns You Off About Evaluation Software?

An Anonymous Coward asks: "I work at a mid-tier software company (which shall remain nameless, lest I draw attention to myself). Recently we have started making 30 day evaluation versions of our software available for download after prospects register. An email containing a username and password is sent to the registrant a few hours after submission. We have been surprised to find that not a few registrants don't actually go on to download the software. We make the file size and system requirements clear up front. I would guess some slashdot readers get involved in evaluations. What process do you go through? Why might you stop short of actually downloading the software?"