I wrote a post about that thinking it was a bug in start 8.  I almost always move my mouse to the left side of my screen and slide down to the start bar to open up the windows start menu but that doesn't work in Start 8, instead as you said, there is a dead zone that I'm apparently hitting every time that I want to bring up the start bar and use the start8 menu.

My post went unanswered  as they do so many times around here.  I hope they can do something to change this as it's just annoying to me to have to keep moving my mouse around to find the sweet spot to open up the start menu with start 8 installed and this Microsoft induced dead pixel zone.

I managed to find a fix for it, pretty simple and should be able to be easily implemented into Start8 I Imagine! Just a few registry keys have to be edited from a value of 6 to 0, link to the thread here explaining:

http://superuser.com/questions/498576/how-to-disable-sticky-corners-in-windows-8

It'd be awesome if you guys could do this as a simple feature to make it a lot less annoying for other people in the future searching for a way to fix it, by simply having the option in Start8