The yesterday WPML 1.7.4 release didn't go so well due to a bug that managed to slip through. The translated homepages of sites using the 'page on front' WP option and the WPML's 'Different languages in directories' setting were affected – instead of showing the translated homepage, the blog page or a 404 page was being displayed.
Luckily, thanks to a number of well intentioned users on our forum, we've been able to track it down and fix it today. Before we did that, in order to avoid having more sites get affected by this bug we released WPML 1.7.5 which as an intermediary version and which is actually the latest stable version before 1.7.4.
WPML 1.7.6 includes everything 1.7.4 did except that unfortunate bug.